<PAGE>

                                                                   EXHIBIT 10.25

                                DATED      2000
                                ---------------

                              TIPACRE LIMITED (1)

                        ADAPTIVE BROADBAND LIMITED (2)

                      ADAPTIVE BROADBAND CORPORATION (3)

--------------------------------------------------------------------------------

                           Counterpart/
                                     LEASE

                                     -of-

                           Part Ground Floor Block C
                  The Westbrook Centre Milton Road Cambridge

--------------------------------------------------------------------------------

                                    MANCHES
                                 Aldwych House
                                  81 Aldwych
                                London WC2B 4RP

                              Tel: 020 7404 4433

                              Ref: PDS/14392/0125

                               Date: 04/02/2000

                                                   MANCHES [LOGO]
<PAGE>

PARTICULARS

DATED                                                                      2000

HEADLEASE/UNDERLEASE        this Lease is a head lease and is a new Lease under
                            the Landlord and Tenant (Covenants) Act 1995

PARTIES
Landlord                    TIPACRE LIMITED
                            Registered office: 8 Exchange Quay Manchester M5 3EJ
                            (Company registration number 01604203)

Tenant                      ADAPTIVE BROADBAND LIMITED
                            Registered office: 47 Castle Street Reading RG1 7SR
                            (Company registration number 03552746)

GUARANTOR                   ADAPTIVE BROADBAND CORPORATION a company registered
                            in the State of California USA
                            Registered office: 1143 Borregas Avenue Sunnygrade
                            CA 94089 USA
                            (Company registration number (N/A))

PROPERTY AND CENTRE
Property                    All the property known as the Part Ground Floor
                            Block C of the Centre shown for identification edged
                            red on the plan numbered '1' annexed and any
                            alterations or additions to it together with all
                            fixtures and fittings in the nature of Landlord's
                            fixtures and fittings and plant and machinery and
                            other service installations which are now or may in
                            the future be affixed to or on the Property

Centre                      All the land and buildings known as the Westbrook
                            Centre Milton Road Cambridge shown for
                            identification edged blue on the plan numbered '2'
                            annexed and registered at H M Land Registry under
                            title number CB59294
<PAGE>

                                 [FLOOR PLAN]
<PAGE>

                                  [SITE PLAN]
<PAGE>

                                  [SITE PLAN]
<PAGE>

CONTRACTUAL TERM              From and including the     day of        2000
                              hereof until the 24th day of June 2009

RENT
Amount                        From and including the date hereof the sum of
                              (Pounds) per annum exclusive

Rent Commencement Date        the     day of     2000

First Rent Payment Date       the     day of     2000

PERMITTED USE                 offices with Class B1 of the Schedule to the Town
                              and Country Planning (Use Classes) Order 1987 as
                              originally enacted but EXCLUDING any or all of the
                              following uses:

                              (a)  Industrial use of any kind except for
                                   research and development purposes

                              (b)  Use by any Government Department in
                                   connection with the provision of services to
                                   or regular access of the public (as distinct
                                   from using the Property for the purposes of
                                   administration and purposes ancillary
                                   thereto)

RENT REVIEW DATE              the 29/th/ day of September 2004

BASIC SERVICE CHARGE
Amount                        TWELVE THOUSAND POUNDS ((Pounds)12,000)

Service Charge Year End Date  31/st/ December

TERMINATION PAYMENT           the sum of (Pounds) plus Value Added Tax
<PAGE>


                                     INDEX

<TABLE>
<CAPTION>
<S>                                                                                                      <C>
1.       DEFINITIONS................................................................................     1

2.       INTERPRETATION.............................................................................     7

     2.1.     Rights of Landlord....................................................................     7
     2.2.     Act or default of the Tenant..........................................................     7
     2.3.     Approval of any superior landlord and mortgagee.......................................     7
     2.4.     Consent and approval of the Landlord..................................................     7
     2.5.     English law...........................................................................     8
     2.6.     Gender and number.....................................................................     8
     2.7.     General and particular words..........................................................     8
     2.8.     Headings..............................................................................     8
     2.9.     Joint and separate obligations........................................................     8
     2.10.      Landlord's liability................................................................     8
     2.11.      Last year and end of the Tenancy....................................................     8
     2.12.      Perpetuity period...................................................................     8
     2.13.      Person and party....................................................................     9
     2.14.      Rights and obligations..............................................................     9
     2.15.      Statute.............................................................................     9
     2.16.      Superior landlord...................................................................     9
     2.17.      Tenant not to allow act.............................................................    10

3.       LETTING....................................................................................    10

     3.1.     Letting...............................................................................    10
     3.2.     Rights subjections and reservations...................................................    10

4.       TENANT'S RIGHTS............................................................................    10

     4.1.     Conducting Media and Common Parts.....................................................    10
     4.2.     Entry for repair......................................................................    11
     4.3.     Support and protection................................................................    11
     4.4.     Nameboard.............................................................................    11
     4.5.     Car Parking...........................................................................    11

5.       SUBJECTIONS AND LANDLORD'S RIGHTS..........................................................    12

     5.1.     Entry by Landlord.....................................................................    12
     5.2.     Letting board etc.....................................................................    13
     5.3.     Goods left on the Property............................................................    13
     5.4.     Conducting Media......................................................................    13
     5.5.     Light and support etc.................................................................    13
     5.6.     Landlord's right to carry out works on other premises.................................    14
     5.7.     Variation of implied rights...........................................................    14
     5.8.     Fire escape...........................................................................    14

6.       TENANT'S COVENANTS.........................................................................    14

     6.1.     Rent..................................................................................    14
     6.2.     Outgoings.............................................................................    15
     6.3.     Interest..............................................................................    16
     6.4.     Repair and decoration.................................................................    16
     6.5.     Maintenance...........................................................................    17
     6.6.     Repair on notice......................................................................    17
     6.7.     Compliance with statutory requirements etc............................................    18
     6.8.     Restrictions on dealings..............................................................    18
     6.9.     Registration of assignments etc.......................................................    22
     6.10.      Information.........................................................................    23
     6.11.      Alterations.........................................................................    23
     6.12.      Signs...............................................................................    24
     6.13.      Cost of removal by Landlord of unauthorised signs etc...............................    24
     6.14.      Service installations...............................................................    24
</TABLE>
<PAGE>

<TABLE>
<S>                                                                                                     <C>
     6.15.    Nuisance..............................................................................    24
     6.16.    Use ..................................................................................    25
     6.17.    Overloading...........................................................................    25
     6.18.    Notices...............................................................................    25
     6.19.    Planning..............................................................................    25
     6.20.    Encroachments.........................................................................    26
     6.21.    Defective Premises....................................................................    26
     6.22.    Landlords rights......................................................................    26
     6.23.    Landlords costs.......................................................................    26
     6.24.    Indemnities...........................................................................    27
     6.25.    Yield up..............................................................................    27
     6.26.    VAT...................................................................................    27
     6.27.    Common Parts and Retained Parts.......................................................    28
     6.28.    Regulations...........................................................................    28
     6.29.    Security..............................................................................    28

7.       LANDLORD'S COVENANTS.......................................................................    29

     7.1.  Quiet Enjoyment..........................................................................    29
     7.2.  Provision of services....................................................................    29
     7.3.  Repair of main structure etc.............................................................    30

8.       INSURANCE..................................................................................    30

     8.1.  Landlord to insure.......................................................................    30
     8.2.  Additional Landlord's fixtures...........................................................    31
     8.3.  Landlord to inform Tenant of insurance cover.............................................    31
     8.4.  Damage to Centre ........................................................................    31
     8.5.  Option to terminate following damage by an Insured Risk..................................    32
     8.6.  Option to terminate following damage by an Excluded Risk.................................    32
     8.7.  Application by the Tenant for new lease following termination............................    33
     8.8.  Tenant's obligations in respect of Landlord's insurances.................................    34
     8.9.  Tenant's insurance.......................................................................    35

9.       SUSPENSION OF RENT.........................................................................    35

     9.1.  Application..............................................................................    35
     9.2.  Suspension...............................................................................    35
     9.3.  Disputes.................................................................................    35

10.      FORFEITURE.................................................................................    35

11.      DECLARATIONS WARRANTIES AND MISCELLANEOUS..................................................    36

     11.1.    Representations and exclusion of use warranty.........................................    36
     11.2.    Accidents.............................................................................    37
     11.3.    Payments recoverable as rent..........................................................    37
     11.4.    Service of notices....................................................................    37
     11.5.    Jurisdiction of the English courts....................................................    37
     11.6.    No prior agreement....................................................................    38
     11.7.    Tenant's option to terminate..........................................................    38

12.      ARBITRATION OR DETERMINATION BY EXPERT.....................................................    38

     12.1.    Contrary Provision....................................................................    38
     12.2.    Arbitration...........................................................................    38
     12.3.    Determination by an expert............................................................    39
     12.4.    Expert's terms of appointment.........................................................    39
     12.5.    Experience of arbitrator or expert....................................................    40
     12.6.    Non-payment of costs of arbitrator or expert..........................................    40

13.      RENT REVIEW................................................................................    40

     13.1.    Definitions...........................................................................    40
     13.2.    Upwards Only Rent Review..............................................................    43
     13.3.    Agreement or Determination of the Reviewed Rent.......................................    43
</TABLE>
<PAGE>

<TABLE>
<S>                                                                                                     <C>
     13.4.    Interim payments until the Open Market Rent is decided................................    44
     13.5.    Rent Restrictions.....................................................................    44
     13.6.    Memorandum of Reviewed Rent...........................................................    45
     13.7.    Time not of the essence...............................................................    45

14.      SERVICE CHARGE.............................................................................    45

     14.1.    Definitions...........................................................................    45
     14.2.    Basic Service Charge..................................................................    46
     14.3.    Adjustment............................................................................    46
     14.4.    Expenditure...........................................................................    47
     14.5.    Deductions in arriving at Expenditure.................................................    51
     14.6.    Landlord's contribution to Expenditure................................................    51
     14.7.    Certificate...........................................................................    51
     14.8.    No implied obligation.................................................................    52

15.      GUARANTOR'S COVENANT.......................................................................    52

FIRST SCHEDULE - FORM OF AUTHORISED GUARANTEE AGREEMENT.............................................    54

SECOND SCHEDULE - FORM OF GUARANTEE COVENANT........................................................    56
</TABLE>
<PAGE>

1.   DEFINITIONS

     In this Lease the following definitions apply:

     "1995 Act"               the Landlord and Tenant (Covenants) Act 1995

     "Arbitration"            arbitration under clause 12.2

     "Base Rate"              the base rate from time to time of Lloyds Bank Plc
                              or if there is no such rate the most closely
                              comparable rate of interest to be determined (if
                              not agreed) by Arbitration

     "Basic Service Charge"   the Basic Service Charge for the time being under
                              clause 14.2

     "Centre"                 the land and building described in the Particulars
                              (including any additions) of which the Property
                              forms part together with any additions to the land
                              and/or buildings comprising the Centre from time
                              to time

     "Common Parts"           the parts of the Centre that are provided and/or
                              designated by the Landlord from time to time for
                              common use by the tenants and occupiers of the
                              Centre and their visitors including for example
                              approaches entrances entrance halls staircases
                              corridors toilets lifts escalators roads ramps car
                              parking areas and fire escapes

     "Conducting Media"       all conducting media including (but not limited
                              to) pipes flues ducts wires cables drains sewers
                              gutters gullies and channels and their ancillary
                              plant and equipment

     "Excluded Risk"          any risk which would have fallen within the
                              definition of "Insured Risks" but for the Landlord
                              exercising its reasonable discretion to exclude
                              the risk from that definition
<PAGE>

     "Fair Proportion"        the fair proportion reasonably determined from
                              time to time by the Landlord's Surveyor

     "Group Company"          a company which is a member of the same group as
                              the Landlord or the Tenant (as the case may be)
                              and for the purpose of this definition:

                              (a)  a company is a "subsidiary" of. another
                                   company if that other company

                                   (i)   holds a majority of the voting rights
                                         in it or

                                   (ii)  is a member of it and has the right to
                                         appoint or remove a majority of its
                                         board of directors or

                                   (iii) is a member of it and controls (alone
                                         or under an agreement with other
                                         shareholders or members) a majority of
                                         the voting rights in it

                              (b)  two companies shall be taken to be members of
                                   the same group if and only if:

                                   (i)   one is a subsidiary of the other or

                                   (ii)  both are subsidiaries of a third or

                                   (iii) one is a subsidiary of a company which
                                         itself is a subsidiary of the other

     "Insurance Rent"         a sum equal to a Fair Proportion of the cost of
                              the insurances described in clause 8.1 (including
                              the cost of any insurance valuations)
<PAGE>

     "Insured Risks"          (a)  fire explosion and lightning

                              (b)  impact

                              (c)  earthquake

                              (d)  aircraft (other than hostile aircraft) and
                                   things dropped from aircraft

                              (e)  flood storm and tempest

                              (f)  bursting or overflowing of water tanks and
                                   apparatus

                              (g)  riot and Civil commotion and

                              (h)  malicious damage

                              and any other risks against which the Landlord or
                              any superior landlord may from time to time
                              reasonably insure and an "Insured Risk" means one
                              of the risks except that a risk will not be an
                              "Insured Risk" to the extent that (in the
                              reasonable opinion of the Landlord's Surveyor)
                              insurance cover is not available in the normal
                              market at a reasonable premium and the Landlord
                              elects not to take out such insurance cover for
                              the Centre

     "Landlord"               the person named in the Particulars or any other
                              person who at the relevant time is entitled to the
                              immediate reversion to this Lease

     "Landlord's Surveyor"    the person(s) from time to time appointed by the
                              Landlord to act as its surveyor for any purpose
                              under this Lease who may be an employee of the
                              Landlord

     "Lease"                  this lease as varied and supplemented by any
                              document

     "Original Landlord"      the person named as Landlord in the Particulars
<PAGE>

     "Original Tenant"        the person named as Tenant in the Particulars

     "Planning Acts"          the Local Government Planning and Land Act 1980
                              the Town and Country Planning Act 1990 the
                              Planning (Listed Buildings and Conservation Areas)
                              Act 1990 the Planning (Hazardous Substances) Act
                              1990 the Planning (Consequential Provisions) Act
                              1990 and the Planning and Compensation Act 1991
                              and any later similar legislation

     "Planning Control"       has the meaning given to it by the Town and
                              Country Planning Act 1990

     "President of the RICS"  the President for the time being of The Royal
                              Institution of Chartered Surveyors or the person
                              for the time being authorised to act on his behalf

     "Property"               the premises described in the Particulars
                              including:

                              (a)  plaster surfaces and decorative and other
                                   finishes on walls columns and other
                                   structures

                              (b)  the inner half of any non-loadbearing walls
                                   and other non-loadbearing structures dividing
                                   the Property from other parts of the Centre

                              (c)  any non-loadbearing internal walls and other
                                   non-loadbearing structures wholly within the
                                   premises

                              (d)  floors (including any raised floors and their
                                   supports floor boards floor screeds and other
                                   floor finishes) down to (but excluding) the
                                   floor slabs or floor joists
<PAGE>

                              (e)  ceilings (including any suspended ceilings
                                   and their fixings ceiling tiles and other
                                   ceiling finishes) up to (but excluding) the
                                   ceiling slabs or ceiling joists

                              (f)  doors including their frames furniture and
                                   any glass

                              (g)  window glass

                              (h)  Conducting Media within the Centre which
                                   exclusively serve the premises and do not
                                   belong to suppliers and central heating
                                   radiators and other heating equipment within
                                   the Property and including the comfort
                                   cooling equipment serving the Property
                                   located both within and outside the Property

                              (i)  landlord's fixtures in or forming part of the
                                   premises and

                              (j)  any additions to the Property

                              but excluding:

                              (k)  loadbearing walls loadbearing columns and
                                   other loadbearing structures (other than
                                   plaster surfaces and decorative and other
                                   finishes)

                              (l)  tenant's fixtures

                              (m)  Conducting Media within the premises which do
                                   not exclusively serve the premises and

                              (n)  all other parts of the Centre not expressly
                                   included in items (a) to (j) (inclusive) of
                                   this definition

     "Retained Parts"         all parts of the Centre other than those parts
                              which are let or intended for letting
<PAGE>

                              and the "Retained Parts" include:

                              (a)  the Common Parts

                              (b)  any office accommodation for staff

                              (c)  any staff rooms and storage premises used to
                                   provide services for the Centre

                              (d)  any accommodation for resident staff

                              (e)  any security system which is operated by the
                                   Landlord

                              (f)  the Conducting Media except to the extent
                                   they form part of the Property or premises
                                   which are let or intended for letting

                              (g)  the plant rooms and other areas which house
                                   or contain Conducting Media forming part of
                                   the Retained Parts and

                              (h)  the walls foundations and roofs of the Centre
                                   except to the extent they form part of the
                                   Property or other premises which are let or
                                   intended for letting

     "Service Charge"         the amount payable by the Tenant for services in
                              the manner described in clause 14

     "Signs"                  signs notices placards stickers advertisements
                              flags logos lettering and numerals

     "the Standard Hours"     Every day from 7.30 am to 10.00 pm except (if the
                              Landlord so reasonably decides) Bank and Public
                              Holidays as reasonably varied from time to time by
                              the Landlord
<PAGE>

            to "approved" and "authorised" and words to similar effect mean
            previously approved or previously authorised in both cases in
            writing

     2.5.   English law

            This Lease shall be governed by and interpreted in accordance with
            English law

     2.6.   Gender and number

            Words of one gender include all other genders and singular words
            include the plural and vice versa

     2.7.   General and particular words

            General words are not limited because they are preceded or followed
            by particular words in the same category or covering the same topic

     2.8.   Headings

            Any footnote heading index marginal note table of contents and
            underlining is for guidance only not interpretation

     2.9.   Joint and separate obligations

            If an obligation is owed to or by more than one person that
            obligation is owed to or by those persons separately jointly or in
            any combination

     2.10.  Landlord's liability

            If the Original Landlord ceases to be the Landlord its liability
            under this Lease ends except in respect of the period before it
            ceases to be the Landlord

     2.11.  Last year and end of the Tenancy

            References to the last year of the Tenancy or other periods related
            to the end of the Tenancy and words to similar effect include the
            last year of the Tenancy or such other period (as the case may be)
            even if it ends before the end of the Contractual Term and
            references to the end of the Tenancy and words to similar effect are
            to be similarly interpreted

     2.12.  Perpetuity period

            The perpetuity period applicable to this Lease is eighty (80) years
            from the start of the Contractual Term and whenever in this Lease
            any party is granted a future interest that interest must vest
            within such perpetuity period and if it has not it will be void
            for remoteness
<PAGE>

     2.13.  Person and party

            2.13.1.  Any reference to a person includes a company corporation or
                     other legal entity

            2.13.2.  Any reference to "parties" or "party" means the Landlord
                     and the Tenant or either or them but (in the absence of a
                     specific reference to the contrary) does not include any
                     Guarantor

     2.14.  Rights and obligations

            2.14.1.  The Tenant or any undertenant or occupier of the Property
                     will not during the Tenancy acquire any implied or
                     prescriptive right or easement from or over or affecting
                     any neighbouring premises in which the Landlord from time
                     to time has a freehold or leasehold interest

            2.14.2.  Rights granted are not exclusive to the Tenant

            2.14.3.  Rights and obligations are cumulative

     2.15.  Statute

            Any reference to a specific statute includes:

            2.15.1.  any statutory extension variation or re-enactment of the
                     statute whether before or after the date of this Lease

            2.15.2.  derivative orders regulations and permissions

            2.15.3.  directives and regulations adopted by the European Union

            Any general reference to "statute" includes those enacted after the
            date of this Lease and includes all derivative orders regulations
            and permissions

     2.16.  Superior Landlord

            2.16.1.  Any reference to a superior landlord includes the
                     Landlord's immediate reversioner and any superior landlord

            2.16.2.  Any reference to a superior lease includes the lease under
                     which the Landlord holds the Property and any lease
                     superior to that

            2.16.3.  When a superior landlord performs a landlord's obligation
                     it will be deemed to have been performed by the Landlord
<PAGE>

     2.17.  Tenant not to allow act

            An obligation by the Tenant not to do an act includes an obligation
            not to knowingly allow that act to be done by another person

3.   LETTING

     3.1.   Letting

            The Landlord lets the Property to the Tenant for the Contractual
            Term the Tenant paying during the Tenancy the following (all of
            which are reserved as rent):

            3.1.1.  from and including the Rent Commencement Date the Rent by
                    equal quarterly payments in advance on the usual quarter
                    days the first payment being due on the First Rent Payment
                    Date

            3.1.2.  from and including the date of this Lease the Insurance Rent
                    within fourteen (14) days after a written demand

            3.1.3.  from and including the date of this Lease the Basic Service
                    Charge by equal quarterly payments in advance on the usual
                    quarter days the first payment being due today

            3.1.4.  any Excess Service Charge in accordance with clause 14 and

            3.1.5.  any VAT payable on the above amounts

     3.2.   Rights subjections and reservations

            The letting includes the rights granted by clause 4 but is subject
            to the subjections (if any) exceptions and reservations set out in
            clause 5

4.   TENANT'S RIGHTS

     The Landlord grants to the Tenant the following rights:

     4.1.   Conducting Media and Common Parts

            The right (subject to reasonable interruption for repair maintenance
            alteration or replacement) to use:

            4.1.1.  the Conducting Media in the Centre which do not form part of
                    the Property but which service the Property and

            4.1.2.  the Common Parts for all proper purposes in connection with
                    the use and enjoyment of the Property
<PAGE>

     4.2.   Entry for repair

            The right to enter other parts of the Centre with workmen and
            equipment to carry out works of repair maintenance decoration or
            alteration to the Property on the following terms and conditions:

            4.2.1.  the Tenant must give reasonable written notice to the
                    Landlord and the occupiers of the relevant premises of its
                    intention to exercise this right

            4.2.2.  the Tenant may only exercise this right in so far as such
                    works cannot be carried out from inside the Property in a
                    commercially practicable manner

            4.2.3.  the Tenant must cause as little inconvenience as reasonably
                    practicable and

            4.2.4.  the Tenant must indemnify the Landlord and the occupiers
                    against the reasonable cost (including reasonable fees) of
                    making good all damage to the premises entered and to the
                    fixtures and contents of such premises caused by such entry

            4.2.5.  the Tenant may only exercise this right to the extent that
                    (if at all) it is reserved out of any other tenancies of the
                    Centre from time to time and subject to any restrictions or
                    conditions or entry contained in such tenancies

     4.3.   Support and protection

            The right of support and protection that is now enjoyed from the
            remainder of the Centre

     4.4.   Nameboard

            The right at the cost of the Tenant to have the Tenant's name
            displayed by the Landlord in a manner approved by the Landlord on:

            4.4.1.  any nameboard in the entrance hall of the building forming
                    part of the Centre in which the Property is situate and

            4.4.2.  any external nameboard at the entrance to the Centre

     4.5.   Car Parking

            The right to park not more than ten (10) private motor vehicles in
            the car parking spaces forming part of the Centre numbered shown for
            identification 52, 53, 100, 101, 222, 223, 224, 225, 226 and 227 on
            the plan numbered '2' annexed or such other ten (10) spaces from
            time to time allocated by the Landlord
<PAGE>

5.   SUBJECTIONS AND LANDLORD'S RIGHTS

     The letting is subject to the following:

     All covenants conditions restrictions and other matters contained mentioned
     or referred to in the registered title to the Centre to the extent that
     such matters relates to the tenancy hereby granted and are still subsisting
     and capable of taking effect but excluding any entries relating to
     mortgages or charges

     The following rights are excepted and reserved to the Landlord:

     5.1. Entry by Landlord

          5.1.1.  The right at reasonable times and on reasonable notice (but in
                  case of emergency at any time without notice) to enter the
                  Property with necessary materials and appliances to:

                  5.1.1.1     view and record the condition of the Property

                  5.1.1.2     repair maintain alter or clean other premises

                  5.1.1.3     inspect repair maintain alter replace or add to
                              Conducting Media

                  5.1.1.4     comply with obligations or exercise any rights
                              under this Lease or a superior lease or any
                              tenancy of another part of the Centre

                  5.1.1.5     carry out any repairs to or decoration of the
                              Property which are not the responsibility of the
                              Tenant

                  5.1.1.6     make good any failure by the Tenant to repair
                              maintain or decorate the Property in compliance
                              with clause 6.6.1

                  5.1.1.7     remove anything which has been fixed placed
                              displayed or left on the Property in breach of
                              clause 6.11 or clause 6.12

                  5.1.1.8     make good any other breach of covenant by the
                              Tenant

                  5.1.1.9     show prospective tenants and purchasers over the
                              Property or

                  5.1.1.10    do any other reasonable thing connected with the
                              Property other than altering the Property
<PAGE>

          5.1.2.  In exercising these rights the Landlord will:

                  5.1.2.1     cause as little inconvenience to the Tenant as is
                              reasonably practicable

                  5.1.2.2     as soon as reasonably practicable make good any
                              damage to the Property caused by the entry and

                  5.1.2.3     indemnify the Tenant against any damage to the
                              tenant's fixtures caused by the entry

     5.2. Letting board etc

          The right during the last six (6) months of the Tenancy to display a
          letting board on the Property and at any time to display a sale board
          on the Property but not so that any such board unreasonably obstructs
          the light or air to the Property

     5.3. Goods left on the Property

          5.3.1.  The right to sell as agent for the Tenant any belongings of
                  the Tenant left in the Property for more than fourteen (14)
                  days after the end of the Tenancy unless the Tenant remains in
                  occupation of the Property under a new tenancy and if the
                  Landlord exercises this right the Tenant will indemnify the
                  Landlord against any liability incurred by the Landlord to
                  anyone whose belongings are sold by the Landlord in the
                  mistaken belief held in good faith (which shall be presumed
                  unless the contrary is proved) that such belongings were owned
                  by the Tenant

          5.3.2.  In the event of a sale the Landlord will account to the Tenant
                  for the proceeds of sale less the reasonable costs of removal
                  storage and sale if the Tenant claims the proceeds of sale
                  within six (6) months after the date on which the Tenant left
                  the Property but if no such claim is made by the Tenant the
                  proceeds of sale will belong to the Landlord

     5.4. Conducting Media

          The right to use the Conducting Media forming part of the Property
          which serve other premises

     5.5. Light and support etc

          The right of light air support and protection and all other easements
          and rights now or after the date of this Lease belonging to or enjoyed
          by any other premises
<PAGE>

     5.6. Landlord's right to carry out works on other premises

          5.6.1.  The right to alter add to and carry out works on other parts
                  of the Centre including the Common Parts or other premises
                  even though this obscures or obstructs any window in the
                  Property or interferes with any rights easements or amenities
                  enjoyed by the Property (for example: rights of access of
                  light and air)

          5.6.2.  In carrying out any works under this clause 5.6 the Landlord
                  will:

                  5.6.2.1     entitled (if reasonably necessary) to erect
                              scaffolding which can be attached to the Property

                  5.6.2.2     take all reasonable precautions to ensure that the
                              beneficial use and occupation of the Property is
                              not materially adversely affected and as soon as
                              reasonably practicable make good any damage caused
                              to the Property and

                  5.6.2.3     ensure that after completion of the works the use
                              of the Property for any purpose permitted by this
                              Lease has not been materially adversely affected

     5.7. Variation of implied rights

          The right to terminate or vary any implied right from time to time
          enjoyed by the Property provided that such termination or variation
          does not materially adversely affect the use of the Property for any
          purpose permitted by this Lease

     5.8. Fire escape

          The right to pass through the Property for the purposes of escape from
          other parts of the Centre or other premises adjoining the Centre in
          case of fire or other emergency

6.   TENANT'S COVENANTS

     The Tenant covenants with the Landlord:

     6.1. Rent

          6.1.1.  To pay the Rent and other amounts in the manner specified in
                  clause 3.1
<PAGE>

          6.1.2.  Not to claim or exercise any right to set-off or to withhold
                  payment of any amounts due to the Landlord (save as required
                  by statute)

          6.1.3.  If required by the Landlord to make payments to the Landlord
                  by banker's order or credit transfer to a bank account in the
                  United Kingdom nominated by the Landlord

     6.2. Outgoings

          6.2.1.  To pay and to indemnify the Landlord against existing and
                  future rates taxes assessments impositions and outgoings
                  assessed or imposed on or in respect of the Property
                  (including those assessed or imposed on the Landlord and any
                  superior landlord) except any taxes (save for VAT which the
                  Tenant is otherwise obliged to pay) assessed or imposed on the
                  Landlord or any superior landlord in respect of:

                  6.2.1.1     the rents

                  6.2.1.2     the grant of this Lease

                  6.2.1.3     any dealing or deemed dealing by the Landlord or a
                              superior landlord with its interest in the
                              Property

          6.2.2.  If such an assessment or imposition is:

                  6.2.2.1     made on premises which include the Property and

                  6.2.2.2     paid by the Landlord

                  to pay a Fair Proportion of it to the Landlord within fourteen
                  (14) days after a written demand except any taxes (save for
                  VAT which the Tenant is otherwise obliged to pay) assessed or
                  imposed on the Landlord or any superior landlord in respect
                  of:

                  6.2.2.3     the rents

                  6.2.2.4     the grant of this Lease

                  6.2.2.5     any dealing or deemed dealing by the Landlord or a
                              superior landlord with its interest in the
                              Property

          6.2.3.  To indemnify the Landlord against any loss of rating relief on
                  the Property after the end of the Tenancy caused by the
                  Property being left empty during the Tenancy
<PAGE>

     6.3. Interest

          6.3.1.  If required by the Landlord to pay interest at a yearly rate
                  of four per cent (4%) above Base Rate on any sum payable under
                  this Lease by the Tenant to the Landlord (whether or not
                  formally demanded) that is not paid on its due date and to pay
                  this interest from the due date to the date of payment (both
                  before and after any court judgment) calculated on a daily
                  basis and compounded with rests on the usual quarter days

          6.3.2.  If while a breach of any tenant's covenant continues the
                  Landlord refuses to accept payment of any sum in order not to
                  waive the breach the Tenant will be deemed for the purposes of
                  this clause 6.3 to have failed to pay such sum

          6.3.3.  This clause 6.3 does not prejudice any other right or remedy
                  of the Landlord

     6.4. Repair and decoration

          6.4.1.  To repair and maintain the Property and to keep it clean and
                  in good repair

          6.4.2.  To repair maintain and keep clean and when necessary renew:

                  6.4.2.1     the fixtures in the Property and

                  6.4.2.2     any carpeting provided by the Landlord (or
                              provided by the Tenant in replacement for any
                              carpeting provided by the Landlord) floor tiles
                              and other floorings

                  Any replacement carpeting floor tiles or other floorings must
                  be in the same colour as and of a quality not inferior to that
                  being replaced

          6.4.3.  To redecorate the interior of the Property (including the
                  internal parts of the window frames) in every fifth (5th) year
                  and in the last three (3) months of the Tenancy preparing and
                  painting papering or polishing as appropriate having regard to
                  earlier treatment

          6.4.4.  As often as necessary to clean and treat in an appropriate
                  manner all other external and internal materials surfaces and
                  finishes of the Property

          6.4.5.  In relation to the work referred to in this clause 6.4:
<PAGE>

                  6.4.5.1 to carry out the work with appropriate materials of
                          good quality in a good and workmanlike manner and to
                          the reasonable satisfaction of the Landlord's Surveyor

                  6.4.5.2 to carry out the painting papering and treatment in
                          the last three (3) months of the Tenancy in a colour
                          or colours approved in writing by the Landlord and

                  6.4.5.3 to clean any glass in the doors windows and other
                          lights of the Property at least once a month

          6.4.6.  Damage by an Insured Risk is excepted from the Tenant's
                  liability under this clause 6.4 except to the extent that the
                  insurance money is irrecoverable because of an act or default
                  of the Tenant

          6.4.7.  Damage by an Excluded Risk is (subject to clause 8.7) excepted
                  from the Tenant's liability under this clause 6.4 if the
                  Landlord serves a Non-Reinstatement Notice as a result of such
                  damage

     6.5. Maintenance

          6.5.1.  To keep the Conducting Media which form part of the Property
                  clear and unobstructed and not to do anything which causes an
                  obstruction or damage to any other Conducting Media serving
                  the Property

          6.5.2.  To take all necessary precautions against:

                  6.5.2.1 frost damage to any pipe tank or water apparatus in
                          the Property and

                  6.5.2.2 the bursting or overflowing of any pipe tank or water
                          apparatus in the Property

     6.6. Repair on notice

          6.6.1.  To make good with all practicable speed any failure to repair
                  maintain or decorate the Property for which the Tenant is
                  liable and of which the Landlord has given notice in writing
                  and to start the necessary work within two (2) months after
                  the Landlord's notice (or sooner if necessary) and then
                  diligently to continue and complete the work

          6.6.2.  If the Tenant does not comply with clause 6.6.1 to pay within
                  fourteen (14) days after a written demand the reasonable
<PAGE>

                  costs incurred by the Landlord in carrying out the necessary
                  work including reasonable fees and expenses

     6.7. Compliance with statutory requirements etc

          6.7.1.  Subject to clause 6.7.2 to carry out all works and provide and
                  maintain all arrangements in respect of the Property and the
                  use to which the Property is being put that are necessary in
                  order to comply with the requirements of:

                  6.7.1.1 the Offices Shops and Railway Premises Act 1963 the
                          Fire Precautions Act 1971 the Defective Premises Act
                          1972 and the Health and Safety at Work etc. Act 1974

                  6.7.1.2 any other statute

                  6.7.1.3 any government department local authority or other
                          public or competent authority

                  6.7.1.4 any court of competent jurisdiction and

                  6.7.1.5 any regulation of the European Communities which
                          applies in the United Kingdom

          6.7.2.  Not to carry out any works which the Landlord elects to carry
                  out by serving written notice on the Tenant

          6.7.3.  To pay within fourteen (14) days after a written demand the
                  whole or a Fair Proportion as appropriate of the Landlord's
                  reasonable expenditure (including reasonable fees and
                  expenses) on any works which the Landlord has elected to carry
                  out under this clause 6.7

          6.7.4.  To comply with any other obligations imposed by law relating
                  to the Property or its use

          6.7.5.  Not to do anything in respect of the Property which imposes on
                  the Landlord a liability under any statute to pay any penalty
                  damages compensation or costs

     6.8. Restrictions on dealings

          6.8.1.  Not to assign underlet or mortgage or charge any part (as
                  distinct from the whole) of the Property

          6.8.2.  Not to mortgage or charge the whole of the Property except:

                  6.8.2.1 by way of floating charge or
<PAGE>

                  6.8.2.2 to a bona fide bank or other financial institution
                          with the consent of the Landlord (which is not to be
                          unreasonably withheld or delayed)

          6.8.3.  Not to execute any declaration of trust with regard to the
                  whole or part of the Property and not to hold or occupy the
                  whole or part of the Property as agent for another or
                  otherwise for the benefit of another

          6.8.4.  Not to part with possession or share the occupation of the
                  whole or any part of the Property except by an assignment or
                  underletting of the whole of the Property except that the
                  Tenant may share occupation of the Property with a Group
                  Company so long as:

                  6.8.4.1 no relationship of lessor and lessee is created

                  6.8.4.2 details of any such arrangement are given to the
                          Landlord in advance

                  6.8.4.3 the Landlord is given notice immediately such an
                          arrangement starts and ends

          6.8.5.  not to assign the whole of the Property without the consent of
                  the Landlord (which consent is not to be unreasonably withheld
                  or delayed)

          6.8.6.  For the purposes of Section 19(1)(A) of the Landlord and
                  Tenant Act 1927 it is agreed that the Landlord may withhold
                  its consent in the following circumstances:

                  6.8.6.1 if any of the conditions set out in 6.8.7 below are
                          not satisfied before the date of the assignment

                  6.8.6.2 if the proposed assignee is a Group Company of the
                          Tenant whose financial standing is materially less
                          substantial than the Tenant

                  6.8.6.3 if the proposed assignee enjoys diplomatic or state
                          immunity (unless the proposed assignee is the
                          Government of the United Kingdom of Great Britain and
                          Northern Ireland or any Department of that Government)

                  6.8.6.4 if it is otherwise reasonable for the Landlord to
                          withhold its consent having regard amongst other
                          things to the fact that the outgoing tenant may be
<PAGE>

                         entitled to be released from its liability under the
                         Lease under the 1995 Act

          6.8.7.  The Landlord is entitled for the purposes of Section 19(1)(A)
                  of the Landlord & Tenant Act 1927 to require the following
                  conditions to be satisfied before this Lease is assigned by
                  the Tenant and to make its consent conditional upon any or all
                  of these conditions being satisfied:

                  6.8.7.1 that the Tenant enters into an authorised guarantee
                          agreement (as defined in Section 16 of the 1995 Act)
                          in the form set out in the First Schedule to this
                          Lease with such variations as the Landlord reasonably
                          requires and that any surety for the Tenant guarantees
                          the obligations of the Tenant under such authorised
                          guarantee agreement

                  6.8.7.2 that the proposed assignee enters into direct
                          covenants with the Landlord (whose costs shall be paid
                          by the Tenant) to pay the rents reserved by this Lease
                          and the other sums payable under this Lease including
                          any sums owed or subsequently arising or accruing in
                          respect of any period prior to the assignment and to
                          perform and observe the tenant covenants and the
                          conditions in this Lease throughout the Tenancy unless
                          and until it is released by virtue of the 1995 Act
                          (and if the proposed assignee is more than one person
                          or company these covenants shall be entered into
                          jointly and severally)

                  6.8.7.3 (if it is reasonable for the Landlord to require this)
                          that one or more sureties the financial status of
                          which is acceptable to the Landlord (who shall act
                          reasonably in judging whether their financial status
                          is acceptable) give direct covenants to the Landlord
                          (jointly and severally) that the proposed assignee
                          will pay the rents reserved by this Lease and will
                          perform and observe the tenant covenants and
                          conditions contained in this Lease in the form set out
                          in the Second Schedule to this Lease with such
                          variations as the Landlord reasonably requires

                  6.8.7.4 (if it is reasonable for the Landlord to require this)
                          also to procure that there is deposited with the
<PAGE>

                          Landlord a sum equal to not less than six month's Rent
                          plus VAT potentially payable thereon This sum and all
                          interest on it shall be charged to the Landlord as
                          security for any non-payment of sums due under this
                          Lease and for any non-observance or non-performance of
                          the covenants by the tenant and the conditions
                          contained in this Lease on the basis that it will be
                          repayable to the proposed assignee following any
                          further lawful assignment which is carried out in
                          accordance with the terms of this Lease This sum and
                          all interest on it shall be held on and shall be
                          subject to such other terms as the Landlord may
                          reasonably require

                  6.8.7.5 any other conditions which may be reasonable in the
                          circumstances

          6.8.8.  Any dispute between the Landlord and the Tenant about the
                  interpretation of clauses 6.8.6 and 6.8.7 or about matters
                  arising under them shall be referred to Arbitration

          6.8.9.  Not to underlet the whole of the Property:

                  6.8.9.1 unless the undertenant enters into direct covenants
                          with the Landlord (whose costs shall be paid by the
                          Tenant) to perform and observe all the lessee's
                          covenants and the other provisions contained in this
                          Lease (other than the payment of the rents) so far as
                          they apply to the part of the Property which is to be
                          underlet

                  6.8.9.2 without the previous consent of the Landlord which
                          consent is not to be unreasonably withheld or delayed
                          where the other provisions of this sub-clause 6.8.9
                          have been complied with

          6.8.10. Not to underlet the whole of the Property at a fine or a
                  premium and not to underlet the whole of the Property at a
                  rent less than whichever is the greater of the open market
                  rental value of the Property and the rent payable under this
                  Lease

          6.8.11. Not to be a party to any agreement or arrangement for the
                  commutation in whole or in part of any rent reserved by and
                  payable under any underletting of the Property

          6.8.12. Every permitted underlease must contain:
<PAGE>

               6.8.12.1  covenants by the underlessee (which the Tenant
                         undertakes to enforce) which prevent the underlessee
                         from doing or allowing anything in on or in relation to
                         the Property which would be a breach of any of the
                         Tenant's obligations in this Lease

               6.8.12.2  provisions for the review of the rent reserved by the
                         underlease (which the Tenant hereby undertakes to
                         operate and to enforce) at least every five years to
                         the open market rent on such review date and on similar
                         terms to clause 13 of this Lease

               6.8.12.3  a condition for re-entry if there is a breach by the
                         underlessee of any covenant in the underlease

               6.8.12.4  a covenant prohibiting sub-letting of the whole or
                         part of the premises demised

               6.8.12.5  an agreement sanctioned by an Order of a Court of
                         competent jurisdiction under the terms of Section 38 of
                         the Landlord and Tenant Act 1954 (as amended by Section
                         5 of the Law of Property Act 1969) by which the
                         provisions of Sections 24 to 28 inclusive of the
                         Landlord and Tenant Act 1954 are excluded from the
                         tenancy created by that underletting

       6.8.13. The Tenant will not vary the terms of or accept any surrender of
               any permitted underlease without the consent of the Landlord
               (which consent shall not be unreasonably withheld or delayed)

       6.8.14. The Tenant will not give any bill of sale or other preferential
               security (other than floating charges) on the stock-in-trade or
               personal chattels of the Tenant which are in or on the Property
               from time to time

  6.9. Registration of assignments etc

       6.9.1.  Within one month after its date to produce to the Landlord's
               solicitors a true copy of every assignment underlease charge or
               other document evidencing a devolution of the whole or any part
               of the Property
<PAGE>

       6.9.2.  On production of a document under clause 6.9.1 to pay to the
               Landlord's solicitors a reasonable registration fee of not less
               than twenty-five pounds ((Pounds)25) plus VAT

6.10.  Information

       6.10.1. To produce to the Landlord on request all plans documents and
               other evidence which the Landlord may reasonably require in order
               to be satisfied that the Tenant has complied with its obligations
               under this Lease

       6.10.2. When requested to supply to the Landlord full details of all
               occupations of the Property and derivative interests in the
               Property however remote

6.11.  Alterations

       6.11.1. Not to alter or add to the structure or exterior of the Property

       6.11.2. Not without the Landlord's consent (which shall not be
               unreasonably withheld or delayed) to alter or extend:

               6.11.2.1 the electrical installation (including wiring) in the
                        Property

               6.11.2.2 any gas installation (including piping) in the Property
                        or

               6.11.2.3 any air-conditioning system in the Property

       6.11.3. Not to make any other alteration or addition to the Property
               without the Landlord's consent (which is not to be unreasonably
               withheld or delayed)

       6.11.4. On any application for consent to alter to supply the Landlord
               with two (2) sets of a specification and detailed drawings
               identifying the proposed works

       6.11.5. Not to fix place or leave anything (for example: any aerial
               satellite dish telecommunications equipment lighting shade or
               awning) on the exterior of the Property except with the consent
               of the Landlord which shall not be unreasonably delayed or
               withheld

       6.11.6. If required by the Landlord to reinstate the Property by the end
               of the Tenancy under the supervision and to the reasonable
               satisfaction of the Landlord's Surveyor to the condition it was
               in before the carrying out of any alterations or additions
<PAGE>

          6.11.7. To procure that any alterations or additions to the Property
                  which are permitted by the Landlord are carried out only by
                  contractors approved by the Landlord (which approval shall not
                  be unreasonably withheld or delayed)

   6.12.  Signs

          Not without the approval of the Landlord (which approval shall not be
          unreasonably withheld or delayed) to place or display any Signs on the
          Property which can be seen from outside the Property except the
          Tenant's name displayed on any external doors of the Property

   6.13.  Cost of removal by Landlord of unauthorised signs etc

          If anything is fixed placed displayed or left on the Property in
          breach of clause 6.11 or clause 6.12 to pay to the Landlord within
          fourteen (14) days after a written demand to remove it the reasonable
          cost of removal incurred by the Landlord

   6.14.  Service installations

          6.14.1. To pay to the suppliers and to indemnify the Landlord against
                  all charges for electricity gas water telephone and other
                  services consumed or used at or for the Property (including
                  meter rents)

          6.14.2. To comply with the requirements and regulations of the
                  suppliers of electricity gas water telephone and other
                  services relating to the installations in the Property

          6.14.3. Not to overload the electrical installation in the Property
                  and to ensure that the electrical installation any gas
                  installation and any air-conditioning system are maintained in
                  a safe condition

          6.14.4. Not to interfere with or impose an additional load on any
                  system of heating cooling or ventilation of the Property

          6.14.5. To keep in good and substantial repair the comfort cooling
                  equipment serving the Property located both within and outside
                  the Property and in particular to enter into and maintain a
                  suitable maintenance contract with a reputable engineer or
                  firm of engineers for the regular maintenance and servicing of
                  the equipment

   6.15.  Nuisance

          Not to do anything in relation to the Property or the Centre which
          causes a nuisance damage or annoyance to the Landlord or others
<PAGE>

     6.16.  Use

            6.16.1.  Not to use the Property:

                     6.16.1.1  for any illegal or immoral purpose

                     6.16.1.2  for any offensive noisy or dangerous trade
                               business or manufacture

                     6.16.1.3  as a betting office a booking office a
                               theatrical agency an employment agency or a
                               travel agency

                     6.16.1.4  as a sex establishment (as defined in the Local
                               Government (Miscellaneous Provisions) Act 1983)
                               or

                     6.16.1.5  as offices for diplomatic use

            6.16.2.  To use the Property only for the Permitted Use

     6.17.  Overloading

            Not to overload the Property

     6.18.  Notices

            6.18.1.  To supply the Landlord with a copy of any notice order
                     direction or proposal of any competent authority affecting
                     the Property as soon as possible after it has been received
                     by the Tenant

            6.18.2.  To comply with any such notice order direction or proposal
                     or at the request of the Landlord to make or join with the
                     Landlord in making such objections or representations
                     relating to it as the Landlord may reasonably require

     6.19.  Planning

            6.19.1.  Not to commit any breach of Planning Control

            6.19.2.  To comply with all provisions and requirements under the
                     Planning Acts which affect the Property

            6.19.3.  Not without the Landlord's consent (which consent will not
                     be unreasonably withheld or delayed where the Landlord may
                     not otherwise withhold or delay its consent to the subject
                     matter of such application) to apply for planning
                     permission relating to the Property or to implement any
                     planning permission
<PAGE>

          6.19.4. Unless the Landlord gives written notice to the contrary to
                  carry out before the end of the Tenancy any works required to
                  be carried out to the Property as a condition of any planning
                  permission obtained by or for the Tenant or anyone having an
                  interest in the Property inferior to that of the Tenant and
                  this applies even if the planning permission does not require
                  the works to be carried out until later

    6.20. Encroachments

          6.20.1. Not to stop up darken or obstruct any window at the Property

          6.20.2. So far as possible to preserve all easements and rights
                  enjoyed by the Property and to help the Landlord prevent
                  anyone acquiring any easement or right over the Property

    6.21. Defective Premises

          6.21.1. Promptly to give written notice to the Landlord of any defect
                  in the Property which might result in an obligation on the
                  Landlord to do or to stop doing anything (for example in order
                  to comply with the provisions of this Lease or the duty of
                  care imposed by the Defective Premises Act 1972)

          6.21.2. To display and maintain all notices relating to the condition
                  of the Property which the Landlord reasonably requires the
                  Tenant to display at the Property

    6.22. Landlord's rights

          To allow the Landlord to exercise its rights under this Lease free
          from interference by the Tenant

    6.23. Landlord's costs

          6.23.1. To pay on an indemnity basis the proper legal charges
                  surveyor's fees bailiff's charges and other costs and expenses
                  reasonably incurred by the Landlord and any superior landlord
                  in relation to:

                  6.23.1.1  applications by the Tenant for the Landlord's
                            consent (save where consent is unlawfully refused
                            but including cases where the application is
                            withdrawn)

                  6.23.1.2  any steps taken in connection with the preparation
                            and service of a schedule of dilapidations or a
                            notice or proceedings under Sections 146 or 147 of
<PAGE>

                              the Law of Property Act 1925 (even if forfeiture
                              is avoided)

                    6.23.1.3  the recovery of any sums due to the Landlord from
                              the Tenant or

                    6.23.1.4  enforcing or requiring the Tenant to remedy a
                              breach of the provisions of this Lease

          6.23.2.   Where the Landlord could recover the cost of advice or
                    services under clause 6.23.1 if undertaken by a third party
                    but the Landlord or a Group Company of the Landlord provides
                    the advice or services to pay to the Landlord the amount
                    that would have been payable by the Tenant if that advice or
                    service had been provided by a third party

 6.24.    Indemnities

          To keep the Landlord indemnified against all liabilities losses and
          expenses incurred by the Landlord arising out of the negligence or
          wrongful act of the Tenant or any breach of the Tenant's covenants in
          this Lease

 6.25.    Yield up

          At the end of the Tenancy to give up the Property:

          6.25.1.  in such state and condition as shall in all respects be
                   consistent with a full and due performance by the Tenant of
                   the covenants on the Tenant's part contained in this Lease

          6.25.2.  clear of any goods and refuse and any tenant's fixtures and
                   with all damage caused by such removal made good

          6.25.3.  with all keys and (where applicable) electronic passes
                   relating to the Property

          6.25.4.  with all Signs put up by the Tenant removed and all damage
                   caused by removal made good

          6.25.5.  with vacant possession

6.26.     VAT

          6.26.1.  To pay to the Landlord and to indemnify the Landlord against
                   any VAT chargeable in respect of:

                   6.26.1.1  the rents payments and other consideration payable
                             or given by the Tenant to the Landlord or
<PAGE>

                  passes to pass into the hands of anyone other than responsible
                  employees of the Tenant

          6.29.3. To lock the external door or doors of the Building following
                  use by the Tenant outside the Standard Hours

7.   LANDLORD'S COVENANTS

     7.1. Quiet Enjoyment

          The Landlord covenants with the Tenant that as long as the Tenant pays
          the rents and complies with the terms of this Lease the Tenant may
          enjoy the Property peaceably during the Tenancy without any
          interruption (except as authorised by this Lease) by the Landlord or
          any person lawfully claiming through under or in trust for the
          Landlord

     7.2. Provision of services

          7.2.1.  During the Standard Hours:

                  7.2.1.1  To keep the Common Parts adequately decorated cleaned
                           (including window-cleaning) and lighted

                  7.2.1.2  In so far as heating equipment exists in the Common
                           Parts to provide such mechanical ventilation heating
                           and cooling for the Common Parts as the Landlord
                           reasonably considers necessary or desirable

                  7.2.1.3  To provide heat to any space heating system in the
                           Property at the date of this Lease (or any system
                           installed by or with the approval of the Landlord in
                           substitution) during such hours and times of year as
                           the Landlord reasonably decides

                  7.2.1.4  To provide sufficient supplies of cold water to the
                           toilet accommodation and hot water to the hot water
                           taps installed in the toilet accommodation in the
                           Common Parts

                  7.2.1.5  To provide an adequate lift service for the Centre
                           and

                  7.2.1.6  To provide such staff (if any) to service and manage
                           the Centre as the Landlord reasonably considers
                           necessary
<PAGE>

          7.2.2.  The Landlord will not be liable for any failure or
                  interruption of any service due to:

                  7.2.2.1  necessary repair replacement or maintenance of any
                           apparatus or installation

                  7.2.2.2  unavoidable shortage of fuel materials water or
                           labour or

                  7.2.2.3  any other cause not due to the act or default of the
                           Landlord

          7.2.3.  The Landlord may extend reduce or otherwise vary the services
                  from time to time if it reasonably considers it desirable to
                  do so for the more efficient operation and management of the
                  Centre or for the comfort of the occupiers in the Centre

     7.3. Repair of main structure etc

          To carry out within a reasonable time those repairs to:

          7.3.1.  the main structure of the Property (including the roof)

          7.3.2.  the Common Parts

          7.3.3.  any other parts of the Centre which give support shelter or
                  protection to the Property and

          7.3.4.  the Conducting Media in the Centre which service the Property
                  jointly with other premises

          that are reasonably necessary for the proper enjoyment of the Property
          by the Tenant but not so as to make the Landlord liable under this
          clause 7.3 for any repairs which are the Tenant's responsibility under
          clause 6

8.   INSURANCE

     8.1. Landlord to insure

          The Landlord will insure the Centre (other than tenant's fixtures) so
          far as such insurance is reasonably available:

          8.1.1.  with a reputable insurance company or with reputable
                  underwriters

          8.1.2.  for the following sums:
<PAGE>

                  8.1.2.1  the full reinstatement value of the Centre (except
                           usual voluntary excesses) including the cost of
                           shoring up demolition and site clearance fees an
                           allowance for inflation and VAT on all such sums

                  8.1.2.2  loss of the Rent reasonably estimated by the
                           Landlord's Surveyor to be payable for three (3) years
                           or such longer period as the Landlord's Surveyor may
                           reasonably consider necessary for planning and
                           carrying out the reinstatement or rebuilding of the
                           Centre

          8.1.3.  against damage or destruction by the Insured Risks and

          8.1.4.  on terms not imposing unreasonable conditions having regard to
                  general market conditions at the time

          8.1.5.  but subject to such excesses exclusions and limitations and
                  other terms as the insurers may impose

     8.2. Additional Landlord's fixtures

          If the Tenant installs fixtures which become landlord's fixtures the
          Tenant will notify the Landlord in writing of the reinstatement value
          so that the Landlord can arrange adequate insurance cover

     8.3. Landlord to inform Tenant of insurance cover

          8.3.1.  The Landlord will produce to the Tenant once in every
                  insurance year reasonable evidence of the terms of the
                  insurance policy and of payment of the current premium

          8.3.2.  The Landlord will notify the Tenant in writing of any material
                  changes in the risks covered and material changes in the terms
                  of the policy with which the Tenant must comply

     8.4. Damage to Centre

          8.4.1.  If the Centre (other than tenant's fixtures) is damaged or
                  destroyed by an Insured Risk:

                  8.4.1.1  unless payment of any of the insurance money is
                           refused because of an act or default of the Tenant

                  8.4.1.2  subject to the Landlord being able to obtain any
                           necessary consents and
<PAGE>

                  8.4.1.3  subject to the necessary labour and materials being
                           and remaining available

                  the Landlord will (subject to clause 8.5) reinstate the
                  damaged part or rebuild the Centre (but not so as to provide
                  accommodation identical in layout if it would not be
                  reasonably practicable to do so) as quickly as reasonably
                  possible

          8.4.2.  The Landlord will use reasonable efforts to obtain the
                  necessary consents (short of making appeals) labour and
                  materials

          8.4.3.  The Tenant will on request vacate the Property and remove its
                  fixtures and effects to allow the Landlord to reinstate the
                  Property

     8.5. Option to terminate following damage by an Insured Risk

          If the whole or a substantial part of the Property is made unfit for
          use by damage or destruction caused by an Insured Risk and:

          8.5.1.  the damage or destruction occurs during the last three (3)
                  years of the Contractual Term or

          8.5.2.  circumstances beyond the control of the Landlord prevent the
                  reinstatement or rebuilding of the Property being started by
                  the third (3rd) anniversary of the date of such damage or
                  destruction

          either the Landlord or the Tenant may terminate this Lease by notice
          in writing to the other The notice may only be given within six (6)
          months after either the date of such damage or destruction under
          clause 8.5.1 or the third (3rd) anniversary referred to in clause
          8.5.2 (as the case may be) On service of the notice this Lease shall
          terminate but without prejudice to any claim of the Landlord or the
          Tenant for an earlier breach of covenant by the other On termination
          of this Lease the insurance money shall belong to the Landlord

     8.6. Option to terminate following damage by an Excluded Risk

          8.6.1.  If the whole or a substantial part of the Centre is made unfit
                  for use by damage or destruction caused by an Excluded Risk
                  the Landlord may elect not to reinstate the Centre

          8.6.2.  Any such election shall be made by the Landlord serving notice
                  in writing ("Non-Reinstatement Notice") on the
<PAGE>

                  Tenant within six (6) months after the date of such damage or
                  destruction

          8.6.3.  If the Landlord serves a Non-Reinstatement Notice:

                  8.6.3.1  the Landlord (despite any other provisions of this
                           Lease) will not be under any obligation to reinstate
                           the Centre and

                  8.6.3.2  either the Landlord or the Tenant may terminate this
                           Lease by notice in writing to the other ("Termination
                           Notice")

          8.6.4.  A Termination Notice may only be given within six (6) months
                  after the date of service of the Non-Reinstatement Notice

          8.6.5.  On service of a Termination Notice:

                  8.6.5.1  this Lease will terminate but without prejudice to
                           the claim of either the Landlord or the Tenant for
                           any earlier breach of covenant by the other

                  8.6.5.2  the insurance money will belong to the Landlord

     8.7. Application by the Tenant for new lease following termination

          8.7.1.  If following:

                  8.7.1.1  termination of this Lease under clause 8.5 or

                  8.7.1.2  service of a Termination Notice under clause 8.6

                  the Tenant makes an application for a new lease of the
                  Property under the Landlord and Tenant Act 1954 then clause
                  8.7.2 will apply

          8.7.2.  Notwithstanding clauses 6.4.6 6.4.7 and 9 the Tenant:

                  8.7.2.1  will so far as possible make good the destruction of
                           or damage to the Property caused by an Insured Risk
                           or an Excluded Risk which gave rise to the
                           termination of this Lease under clause 8.5 or the
                           service of a Termination Notice (as the case may be)
                           and

                  8.7.2.2  will continue paying the Rent the Insurance Rent and
                           the Service Charge from the date of the destruction
                           or damage referred to in clause 8.7.2.1
<PAGE>

     8.8. Tenant's obligations in respect of Landlord's insurances

          8.8.1.  The Tenant will not by act or omission do anything which:

                  8.8.1.1  adversely affects any Landlord's insurance relating
                           to the Centre or

                  8.8.1.2  causes any increase in the insurance premium payable
                           for any such insurance (unless the Tenant has
                           obtained the Landlord's approval and has agreed to
                           pay the additional premium) or

                  8.8.1.3  otherwise prevents the Landlord from renewing any
                           such insurance on terms that would have applied but
                           for the Tenant's act or omission

          8.8.2.  The Tenant will comply with the requirements and proper
                  recommendations of the insurers of the Centre and the fire
                  authority and the proper requirements of the Landlord in
                  respect of the Property relating to:

                  8.8.2.1  explosive and specially flammable articles substances
                           and liquids

                  8.8.2.2  the provision and maintenance of fire fighting
                           equipment and

                  8.8.2.3  fire and safety precautions

          8.8.3.  The Tenant will repay to the Landlord within fourteen (14)
                  days after a written demand all increased premiums paid and
                  all losses and damages suffered by the Landlord as a result of
                  a breach by the Tenant of this clause 8.8

          8.8.4.  The Tenant will immediately inform the Landlord in writing of
                  any circumstance in respect of the Property which might affect
                  or lead to a claim on any Landlord's insurance relating to the
                  Centre

          8.8.5.  If as a result of the Tenant's act or default any insurance
                  money under the insurance policy arranged by the Landlord or a
                  superior landlord (other than in respect of the loss of rents)
                  is wholly or partially irrecoverable the Tenant will pay to
                  the Landlord within fourteen (14) days after a written demand
                  the irrecoverable amount and on payment clause 8.4 shall apply
                  as though the insurance money had been recoverable
<PAGE>

     8.9. Tenant's insurance

          The Tenant will not arrange any insurance of the Property against any
          Insured Risks but if the Tenant has the benefit of any such insurance
          the Tenant will hold all money receivable under such insurance in
          trust for the Landlord

9.   SUSPENSION OF RENT

     9.1. Application

          This clause 9 applies (subject to clause 8.7.2) if the Centre is
          damaged or destroyed by an Insured Risk or (unless caused by the act
          or default of the Tenant) an Excluded Risk so that any part of the
          Property is unfit for use or inaccessible

     9.2. Suspension

          The whole or a Fair Proportion of the Rent according to the extent of
          the damage will be suspended until the earlier of:

          9.2.1.  the date that the whole of the Property (with the necessary
                  services and accesses in the Centre) is again fit for use and

          9.2.2.  the expiration of the period of three (3) years from the date
                  of the damage or if longer the period of the loss of Rent
                  covered by the Landlord's insurance

          except to the extent that payment of any of the insurance money in
          respect of the loss of rents is refused because of an act or default
          of the Tenant

     9.3. Disputes

          Any dispute about this clause 9 shall be settled by Arbitration but if
          before an application is made for the appointment of an arbitrator the
          Landlord so elects by notice in writing served on the Tenant a dispute
          will instead be determined by an independent surveyor

10.  FORFEITURE

     If any of the following events occur:

     10.1 any rents are unpaid for twenty-one (21) days after becoming due
          (whether formally demanded or not)

     10.2 there is a breach by the Tenant or the Guarantor (if any) of any
          covenant or other term of this Lease
<PAGE>

     10.3 the Tenant or the Guarantor (if any) enters into an arrangement or
          composition for the benefit of creditors

     10.4 the Tenant or the Guarantor (if any) being an individual (or if more
          than one individual then any one of them):

          10.4.1  becomes bankrupt

          10.4.2  makes an application to the Court for an interim order under
                  Part VIII of the Insolvency Act 1986 or

          10.4.3  is served with a statutory demand under the Insolvency Act
                  1986

     10.5 the Tenant or the Guarantor (if any) being a body corporate (or if
          more than one of them is a body corporate then any one of them):

          10.5.1  is wound up

          10.5.2  is subject to a resolution by the directors or shareholders to
                  present a petition for an administration order

          10.5.3  has an administration order made in respect of it

          10.5.4  passes a winding-up resolution or enters into liquidation
                  (other than a winding up or liquidation for the purpose of
                  reconstruction or amalgamation of a solvent body corporate) or

          10.5.5  has a receiver or an administrative receiver or a receiver and
                  manager appointed

                                       or

     10.6 execution or distress is levied on the Tenant's goods in the Property

     then the Landlord may by re-entering any part of the Property forfeit this
     Lease and the Tenancy will immediately end but without prejudice to any
     other rights and remedies of the Landlord

11.  DECLARATIONS WARRANTIES AND MISCELLANEOUS

     11.1.  Representations and exclusion of use warranty

            11.1.1.  The Tenant acknowledges that this Lease has not been
                     entered into in reliance on any representation made by or
                     on behalf of the Landlord
<PAGE>

            11.1.2.  Nothing in this Lease or in any consent granted by the
                     Landlord implies a warranty by the Landlord that the
                     Property may be used for any specific purpose under the
                     Planning Acts

     11.2.  Accidents

            The Landlord is not liable to the Tenant nor to any other person
            for:

            11.2.1.  any damage sustained to or loss of any goods or property in
                     the Centre or

            11.2.2.  any other damage loss accident happening or injury not
                     caused or contributed to by the negligence of the Landlord
                     or any employee of the Landlord

     11.3.  Payments recoverable as rent

            Amounts payable by the Tenant and any guarantor under this Lease not
            expressly reserved as rent will be recoverable as if they were rent

     11.4.  Service of notices

            11.4.1.  The provisions of Section 196 of the Law of Property Act
                     1925 as amended by the Recorded Delivery Service Act 1962
                     shall apply to the service of all notices under or in
                     connection with this Lease except that Section 196 shall be
                     deemed to be amended by the deletion of the words "and that
                     service ... be delivered" at the end of Section 196(4) and
                     the substitution of the words "... and that service shall
                     be deemed to be made on the third Working Day after the
                     registered letter has been posted; "Working Day" meaning
                     any day from Monday to Friday (inclusive) other than
                     Christmas Day, Good Friday and any statutory bank or public
                     holiday"

            11.4.2.  For the purposes of notices on Adaptive Broadband
                     Corporation these shall be deemed properly served if sent
                     by post or delivered by hand to the address specified for
                     Adaptive Broadband Limited in this Lease or such other
                     address in the United Kingdom as from time to time notify
                     to the Landlord in writing

     11.5.  Jurisdiction of the English courts

            The parties including any Guarantor submit to the exclusive
            jurisdiction of the English courts on all matters relating to this
            Lease
<PAGE>

     11.6.  No prior agreement

            It is certified that there is no written agreement for lease to
            which this Lease gives effect

     11.7.  Tenant's option to terminate

            The Tenant may terminate this Lease on 29/th/ September 2004 on not
            less than twelve calendar months' notice in writing so long as the
            Tenant has substantially observed and performed all the provisions
            of this Lease and has paid to the Landlord the Termination Payment
            plus Value Added Tax and on expiry of such notice:

            11.7.1.  this Lease will come to an end but without prejudice to the
                     rights of either party against the other for any prior
                     breach of covenant

            11.7.2.  the Tenant will give vacant possession of the whole of the
                     Property and

            11.7.3.  the Tenant will cancel any notice caution or land charge
                     registered to protect this Lease and will if the title to
                     this Lease is registered at H.M. Land Registry assist the
                     Landlord in cancelling the title

12.  ARBITRATION OR DETERMINATION BY EXPERT

     12.1.  Contrary Provision

            Any contrary provision elsewhere in this Lease will override the
            provisions of this clause 12

     12.2.  Arbitration

            12.2.1.  Where this Lease provides for reference to Arbitration a
                     reference will be made in accordance with the Arbitration
                     Act 1996 to a single arbitrator

            12.2.2.  The arbitrator may be appointed by the Landlord and the
                     Tenant jointly but otherwise the arbitrator will be
                     nominated by the President of the RICS on the application
                     of either the Landlord or the Tenant

            12.2.3.  If an appointed or nominated arbitrator dies or declines to
                     act or it becomes clear that he will be unable to complete
                     his duties a replacement will be appointed or nominated by
                     the same process
<PAGE>

     12.3.  Determination by an expert

            12.3.1.  Where this Lease provides for reference to determination by
                     an independent surveyor a reference will be made on the
                     terms of clause 12.4 to the determination of a single
                     independent surveyor

            12.3.2.  The surveyor may be appointed by the Landlord and the
                     Tenant jointly or in the absence of agreement on a joint
                     appointment will be nominated by the President of the RICS
                     on the application of either the Landlord or the Tenant

            12.3.3.  The surveyor will act as an expert (not as an arbitrator)
                     on the terms set out in clause 12.4

     12.4.  Expert's terms of appointment

            12.4.1.  The surveyor will give to the Landlord and the Tenant
                     notice in writing of his appointment and in that notice the
                     surveyor will invite the Landlord and the Tenant to submit
                     within a specified time period (not exceeding four (4)
                     weeks) their respective proposals and representations

            12.4.2.  The surveyor will:

                     12.4.2.1  consider the proposals and representations
                               submitted to him (but not be limited or fettered
                               by them)

                     12.4.2.2  be entitled to rely on his own judgment and
                               opinion

                     12.4.2.3  state any reasons for his decisions and

                     12.4.2.4  within eight (8) weeks after his appointment or
                               within such extended period as the Landlord and
                               the Tenant may agree give the Landlord and the
                               Tenant written notice of his decision and his
                               decision shall be final and binding on the
                               Landlord the Tenant and the Guarantor (if any)

            12.4.3.  If the surveyor:

                     12.4.3.1  does not give notice of his decision within the
                               time and in the manner referred to in clause
                               12.4.2

                     12.4.3.2  resigns from his appointment or

                     12.4.3.3  dies
<PAGE>

                     or if for any reason it becomes clear that he will be
                     unable to complete his duties the Landlord or the Tenant
                     may appoint or apply for the nomination of a new surveyor
                     in his place and this procedure may be repeated as many
                     times as necessary

            12.4.4.  In the absence of a direction by the surveyor as to how his
                     fees or charges are to be borne the Landlord and the Tenant
                     will bear them equally

            12.4.5.  If the provisions for an independent surveyor to determine
                     the issue fail completely the issue will then be referred
                     to Arbitration

     12.5.  Experience of arbitrator or expert

            The arbitrator or independent surveyor will if reasonably
            practicable be a surveyor experienced in the valuation or letting of
            premises similar to the Property

     12.6.  Non-payment of costs of arbitrator or expert

            This clause 12.6 applies if the arbitrator or independent surveyor
            is ready to make his award but is unwilling to do so due to the
            failure by one party to pay its share of the costs of the award If
            one party fails to pay its share of the costs within fourteen (14)
            days after a written request the other party may pay that share and
            any amount so paid will be a debt due immediately from the party in
            default to the other party

13.  RENT REVIEW

     13.1.  Definitions

            In this clause the following definitions apply:

            "Assumptions"          the assumptions (whether or not they are
                                   facts) that on the Relevant Review Date:

                                   (a)  the Property is fit for immediate use
                                        occupation and beneficial trading

                                   (b)  the Property may lawfully be used by any
                                        person for any of the purposes permitted
                                        by this Lease

                                   (c)  no work has been carried out to the
                                        Property by the Tenant or any
<PAGE>

                                        undertenant or their respective
                                        predecessors in title which has
                                        diminished the rental value of the
                                        Property

                                   (d)  that if the Property has been wholly or
                                        partly destroyed or damaged it has been
                                        fully rebuilt and reinstated

                                   (e)  that the Property is in a good state of
                                        repair and decorative condition

                                   (f)  that the Tenant has complied with all
                                        the covenants for which it is liable in
                                        this Lease

          "Determination Date"     the date on which the amount of the reviewed
                                   rent is agreed or is determined by
                                   Arbitration or by an independent surveyor

          "Disregarded Matters"    (a)  any effect on rent of the fact that the
                                        Tenant any permitted undertenant or
                                        their respective predecessors in title
                                        have been in occupation of the Property
                                        or any part of it

                                   (b)  any goodwill attached to the Property
                                        because of the business then carried on
                                        at the Property by the Tenant or any
                                        permitted undertenant

                                   (c)  any increase in the rental value of the
                                        Property attributable to the existence
                                        of any improvement (shown to be an
                                        improvement by the Tenant) to the
                                        Property or any part of it but only if

                                        (i)    the improvement was carried out
                                               with all necessary consents
                                               (where required) and

                                        (ii)   the improvement was
<PAGE>

                                               carried out by the Tenant or any
                                               permitted undertenant and


                                        (iii)  the improvement was not carried
                                               out in pursuance of an obligation
                                               to the Landlord or its
                                               predecessors in title and

                                        (iv)   the improvement was carried out
                                               after the date of this Lease

                                   (d)  any rent free period and/or
                                        concessionary rent and/or after the
                                        giving of any other inducement
                                        (including but not limited to a capital
                                        payment) given or granted to reflect
                                        only the length of time it would take to
                                        carry out the initial fitting out of the
                                        Property

          "Open Market Rent"       the clear yearly rent at which the Property
                                   might reasonably be expected to be let in the
                                   open market:

                                   (i)   by a willing landlord to a willing
                                         tenant of such length or such amount or
                                         on such terms as would be negotiated in
                                         the open market on the letting of the
                                         Property as a whole

                                   (ii)  with vacant possession at the Relevant
                                         Review Date

                                   (iii) by a willing landlord to a willing
                                         tenant

                                   (iv)  without any premium or other
                                         consideration

                                   (v)   for a term commencing on the Relevant
                                         Review Date equal to whichever is the
                                         greater of the
<PAGE>

                                         residue of the Tenancy which then
                                         remains unexpired and 10 years

                                   (vi)  otherwise on the terms and conditions
                                         and subject to the covenants and
                                         provisions contained in this Lease
                                         (other than the amount of rent payable
                                         under this Lease but including the
                                         provisions of this clause 13 for the
                                         review of that rent)

                                   (vii) making the Assumptions but disregarding
                                         the Disregarded Matters

           "Rent Restrictions"     the restrictions imposed by any statute for
                                   the control of rent in force on a Review Date
                                   or on the date on which any increased rent is
                                   calculated in accordance with this clause 13
                                   and which impose any limit whether in time or
                                   amount on the collection of an increase in
                                   the rent or any part of it

           "Review Date"           each of the Rent Review Dates specified as
                                   such in the Particulars and the expression
                                   "Relevant Review Date" will be interpreted
                                   accordingly

     13.2.  Upwards Only Rent Review

            The rent first reserved by this Lease will be reviewed at each
            Review Date in accordance with the provisions of this clause 13 and
            after and including each Review Date will be equal to whichever is
            the higher of

            13.2.1.  the rent contractually payable immediately before the
                     Relevant Review Date

            13.2.2.  the Open Market Rent on the Relevant Review Date as agreed
                     or determined under the provisions of this clause 13

     13.3.  Agreement or Determination of the Reviewed Rent

            The Open Market Rent at any Review Date may be agreed in writing by
            the Landlord or the Tenant at any time but if (for any reason) they
<PAGE>

            have not agreed it by the relevant Review Date either the Landlord
            or the Tenant may thereafter give notice in writing to the other
            requiring the Open Market Rent to be decided by Arbitration or if an
            application is made for the appointment of an arbitrator and the
            Landlord so elects by notice in writing served on the Tenant to be
            decided by an independent surveyor

     13.4.  Interim payments until the Open Market Rent is decided

            If the amount of the reviewed rent has not been agreed or decided by
            Arbitration or by an independent surveyor before the Relevant Review
            Date the Tenant will pay the Landlord:

            13.4.1.  in respect of the period beginning on the Relevant Review
                     Date and ending on the day before the quarter day that
                     follows the Determination Date rent at the yearly rate
                     payable immediately before the Relevant Review Date

            13.4.2.  on the Determination Date on demand and as arrears of rent
                     the amount by which the reviewed rent exceeds the rent
                     actually paid during the period defined in 13.4.1 above
                     (apportioned on a daily basis) together with interest at
                     Base Rate

     13.5.  Rent Restrictions

            Whenever Rent Restrictions prevent or prohibit the operation of this
            clause 13 for the review of the rent or the normal collection or
            retention by the Landlord of any increase in the rent or any
            instalment or part of it:

            13.5.1.  the operation of such provisions for review of the rent
                     will be postponed so that they take effect on the first
                     date or dates thereafter upon which such operation may
                     occur

            13.5.2.  the collection of any increase or increases in the rent
                     will be postponed to take effect on the first date or dates
                     thereafter on which such increase or increases may be
                     collected and/or retained in whole or in part and this
                     postponement will happen however many times as necessary to
                     ensure the collection of the whole of the increase

            13.5.3.  until the Rent Restrictions are wholly or partly relaxed
                     the rent first reserved by this Lease will be the maximum
                     sum permitted by the Rent Restrictions at the time
<PAGE>

     13.6.  Memorandum of Reviewed Rent

            As soon as the amount of any reviewed rent has been agreed or
            decided by Arbitration or by an independent surveyor memoranda
            stating the amount will be prepared by the Landlord or its
            solicitors and will be signed by or on behalf of both the Landlord
            and the Tenant and the parties will each bear their own costs in
            respect of the memoranda

     13.7.  Time not of the essence

            For the purposes of this clause 13 time is not of the essence

14.  SERVICE CHARGE

     14.1.  Definitions

            In this clause the following definitions apply:

            "Excess Service Charge"     the excess calculated in accordance with
                                        clause 14.3

            "Expenditure"               the sum calculated in accordance with
                                        clauses 14.4 and 14.5 which may include:

                                        (a)  reasonable provision for future
                                             expenditure on such of the items in
                                             clause 14.4 as call for
                                             intermittent expenditure (whether
                                             likely to be incurred during or
                                             after the end of the Tenancy) and

                                        (b)  a reasonable sum for depreciation
                                             on the capital costs of machinery
                                             apparatus and equipment

            "Service Charge Year"       a year ending on the date specified in
                                        the Particulars or such other period as
                                        the Landlord may from time to time
                                        decide and notify in writing to the
                                        Tenant

            "Tenant's Proportion"       the Fair Proportion attributable to the
                                        Property which may be determined by
                                        applying different proportions to
                                        different items of Expenditure which
                                        different proportions may depend on
                                        among other things the floor area
                                        rateable value location and use of the
<PAGE>

                                        Property compared with other premises
                                        benefiting from the item of Expenditure
                                        in question

     14.2.  Basic Service Charge

            The Basic Service Charge is payable yearly by equal quarterly
            payments in advance on the usual quarter days and will initially be
            the amount stated in the Particulars but it may be changed from time
            to time to an amount which the Landlord's Surveyor reasonably
            decides and on any increase in the Basic Service Charge the new
            amount will be due and payable on (but not before) the date fourteen
            (14) days after the Landlord has given notice in writing of the new
            amount to the Tenant

     14.3.  Adjustment

            14.3.1.   As soon as practicable after the end of each Service
                      Charge Year the Landlord will deliver to the Tenant a
                      statement showing in reasonable detail the Expenditure and
                      the Tenant's Proportion of the Expenditure for that
                      Service Charge Year

            14.3.2.   In the first statement the Tenant's Proportion of the
                      Expenditure shall be calculated and payable by the Tenant
                      for the period from and including the Service Charge
                      Commencement Date until the end of that Service Charge
                      Year

            14.3.3.   If the Tenant's Proportion of the Expenditure shown by a
                      statement is more than the Basic Service Charge paid in
                      respect of the Service Charge Year the Tenant must within
                      fourteen (14) days after written demand pay to the
                      Landlord the excess

            14.3.4.   If less the Landlord will reduce the next payment of Basic
                      Service Charge or Rent by (or if the tenancy has ended
                      will pay to the Tenant within fourteen (14) days) the
                      difference

            14.3.5.   The provisions of this clause 14 will continue to apply
                      even though the Tenancy has ended but only in respect of
                      the period to the end of the Tenancy

            14.3.6.   For the purpose of calculating the Tenant's Proportion of
                      the Expenditure in respect of an incomplete Service Charge
                      Year:
<PAGE>

                     14.3.6.1  it will not be relevant to ascertain the precise
                               date in that Service Charge Year on which each
                               individual item of Expenditure was incurred

                     14.3.6.2  the Service Charge will be deemed to have accrued
                               at a uniform daily rate over the whole of the
                               relevant Service Charge Year and

                     14.3.6.3  the Service Charge will be apportioned in respect
                               of time only and will be considered as accruing
                               from day to day

                     unless in the reasonable opinion of the Landlord's Surveyor
                     it is unfair that any item should be apportioned on that
                     basis in which case the item will be apportioned on the
                     basis reasonably decided by the Landlord's Surveyor

     14.4.  Expenditure

            14.4.1.  The Expenditure comprises the total cost reasonably and
                     properly incurred by the Landlord (including contributions
                     which the Landlord is liable to make to expenditure
                     incurred by others) in respect of the Centre on the
                     following items (or such of them as are applicable from
                     time to time):

                     14.4.1.1  in performing its obligations under clauses 7.2
                               and 7.3 including providing outside the Standard
                               Hours any of the services referred to in clause
                               7.2

                     14.4.1.2  in providing other services in the interest of
                               good estate management for the proper enjoyment
                               of the Centre by the occupiers

            14.4.2.  In particular the Expenditure will include (but shall not
                     be limited to) the cost reasonably and properly incurred or
                     where relevant deemed incurred by the Landlord on the
                     following items or such of them as are applicable from time
                     to time including a reasonable fee for the Landlord where
                     the Landlord's employees carry out the work:

                     14.4.2.1  insurances including:

                               (a)  insurance of the Landlord and any superior
                                    landlord against third party employers' and
                                    public liability risks in respect of the
                                    Centre
<PAGE>

                                    in connection with the repair and
                                    maintenance of the Centre

                     14.4.2.4  facilities in the Retained Parts including:

                               (a)  providing repairing maintaining renewing
                                    decorating cleaning and altering any
                                    furniture furnishings carpets and other
                                    floor coverings fixtures features and Signs
                                    and

                               (b)  providing maintaining and renewing plants
                                    shrubs trees grassed areas and grown or cut
                                    flowers

                     14.4.2.5  refuse services including:

                               (a)  providing repairing maintaining renewing and
                                    cleaning dustbins paladins and other refuse
                                    containers refuse compactors and other plant
                                    and equipment for the collection treatment
                                    packaging and disposal of refuse and

                               (b)  collecting storing and disposing of refuse

                     14.4.2.6  providing repairing maintaining renewing cleaning
                               and altering the following in the Retained Parts:

                               (a)  lighting heating cooling ventilation and
                                    other equipment and systems

                               (b)  other electrical equipment and systems

                               (c)  surveillance equipment alarms closed-circuit
                                    television entry systems and security and
                                    emergency apparatus and systems

                               (d)  satellite dishes and associated cabling

                               (e)  telecommunications equipment and systems and

                               (f)  fire alarms and ancillary apparatus fire
                                    prevention and fire fighting equipment and
                                    apparatus

                     14.4.2.7  staff including:
<PAGE>

                               (a)  providing and equipping such staff for the
                                    servicing management and security of the
                                    Centre as the Landlord reasonably considers
                                    necessary and

                               (b)  insurance health pension welfare severance
                                    and other payments contributions and
                                    premiums and other benefits in kind and the
                                    costs of accommodation (including notional
                                    rent reasonably assessed by the Landlord's
                                    Surveyor) provided for such staff

                     14.4.2.8  statutory obligations including:

                               (a)  all rates taxes assessments impositions and
                                    outgoings (but not rents) payable by the
                                    Landlord in respect of the Centre as a whole
                                    the Property together with other premises in
                                    the Centre or the whole or any part of the
                                    Retained Parts but not the taxes excepted
                                    under clause 6.2.1

                               (b)  compliance by the Landlord with any notice
                                    regulation or order of any competent
                                    authority any requirement under any present
                                    or future Act of Parliament order byelaw or
                                    regulation and the proper requirements of
                                    the fire officer in respect of the whole
                                    Centre or a part of the Centre which
                                    includes the Property or the Retained Parts

                               (c)  carrying out any works which are required to
                                    obtain a fire certificate for the whole or
                                    any part of the Centre

                     14.4.2.9  miscellaneous matters:

                               (a)  making representations against or otherwise
                                    contesting the provisions of any legislation
                                    order regulation notice or statutory
                                    requirement relating to or affecting the
                                    whole or any part of the Centre

                               (b)  the fees and expenses payable to surveyors
                                    and other consultants and advisers in
                                    connection with the management of the
<PAGE>

                                    Centre health security safety and the
                                    provision of services and

                               (c)  the preparation and audit of any Service
                                    Charge account including any statement of
                                    the Expenditure or of the Tenant's
                                    Proportion

                               (d)  cleaning and keeping clear the outside of
                                    all windows in the Centre and the inside of
                                    windows in the Common Parts

            14.4.3.  The Expenditure will not include:

                     14.4.3.1  any fees and expenses attributable to:

                               (a)  demanding and collecting rents (and rents in
                                    this context shall not mean service charge
                                    or insurance rents) from the tenants and
                                    other occupiers of the Centre and

                               (b)  the grant of leases of other parts of the
                                    Centre

            but this will not prevent the Landlord recovering from the Tenant
            any costs in connection with the recovery of arrear of rents and
            other sums due under this Lease outside the provisions of this
            clause 14 and

                     14.4.3.2  the cost of repairing or making good any damage
                               caused by an Insured Risk under the provisions of
                               clause 8.4 (except that the uninsured excess may
                               be included)

     14.5.  Deductions in arriving at Expenditure

            In calculating the Expenditure the Landlord will deduct all
            contributions which it receives from any person (other than a tenant
            or occupier of the Centre) who makes use of any of the facilities of
            the Centre or benefits from the services

     14.6.  Landlord's contribution to Expenditure

            For the avoidance of doubt the Landlord will bear the proportion of
            the Expenditure which is fairly attributable (according to the
            degree of benefit received by each part of the Centre actually
            benefiting from the relevant service) to the remaining parts of the
            Centre which are intended for letting (whether or not let)

     14.7.  Certificate
<PAGE>

            14.7.1.  Each annual statement of Expenditure (including the
                     Tenant's Proportion) may (at the Landlord's option) be
                     certified by the Landlord's Surveyor

            14.7.2.  Except for manifest error a copy of the certified statement
                     will be conclusive and final and binding on the parties
                     including any Guarantor in respect of the matters covered
                     by the statement other than on questions of law

            14.7.3.  The Landlord will on request allow the Tenant to inspect at
                     reasonable times in the two (2) months after delivery of a
                     statement the vouchers and receipts for the items included
                     in it

     14.8.  No implied obligation

            The inclusion of an item in the list contained in clause 14.4 does
            not imply an obligation by the Landlord to provide the service

15.  GUARANTOR'S COVENANT

            15.1.1.  In consideration of the Landlord granting this Lease to the
                     Original Tenant the Guarantor covenants and guarantees with
                     and to the Landlord as a primary obligation that:

                     15.1.1.1  The Tenant will punctually pay the rents and
                               perform and observe the covenants and other terms
                               of the Lease

                     15.1.1.2  If the Tenant does not pay all or part of the
                               rents or does not perform and observe any or all
                               of the covenants or other terms of the Lease the
                               Guarantor will pay the rents and perform and
                               observe the covenants or terms in respect of
                               which the Tenant is in default and the Guarantor
                               will make good to the Landlord on demand and
                               indemnify the Landlord against all losses damages
                               costs and expenses arising or incurred by the
                               Landlord as a result of such non-payment non-
                               performance or non-observance

            15.1.2.  The Guarantor's liability will not be reduced or ended
                     because:

                     15.1.2.1  of any time or indulgence granted by the Landlord
                               to the Tenant or any neglect or forbearance of
                               the Landlord in enforcing the payment of the
                               rents or
<PAGE>

                               the observance or performance of the covenants or
                               other terms of the Lease

                     15.1.2.2  the terms of the Lease have been varied by
                               agreement between the parties (but this is
                               subject to the provisions of Section 18 of the
                               1995 Act)

                     15.1.2.3  the Tenant has surrendered part of the Property
                               in which case the liability of the Guarantor will
                               continue in respect of the part of the Property
                               which has not been surrendered after making any
                               necessary apportionments under Section 140 of the
                               Law of Property Act 1925

                     15.1.2.4  of any other act or thing by which the Guarantor
                               would have been released if it were not for this
                               provision

           15.1.3.   The Guarantor further covenants with the Landlord that if
                     the Lease is disclaimed before any lawful assignment of it
                     by the Tenant:

                     15.1.3.1  the Landlord may within six months after that
                               disclaimer require the Guarantor to accept a new
                               lease of the Property for a term equivalent to
                               the residue which if there had been no disclaimer
                               would have remained of the Tenancy at the same
                               rent and subject to the same covenants and
                               conditions as were payable under and applicable
                               to the Tenancy immediately before the date of the
                               disclaimer

                     15.1.3.2  such new lease and the rights and liabilities
                               under it will take effect from the date of the
                               disclaimer

                     15.1.3.3  the Guarantor will pay the Landlord's costs
                               incurred in connection with the new lease and the
                               Guarantor will accept the new lease accordingly
                               and will execute and deliver to the Landlord a
                               counterpart of it

            15.1.4.  If the Lease is disclaimed and for any reason the Landlord
                     does not require the Guarantor to accept a new lease of the
                     Property under clause 15.1.3 the Guarantor will pay to the
                     Landlord on demand an amount equal to the difference
                     between any money received by the Landlord for the use or
                     occupation of the Property (less any expenditure incurred
                     by the Landlord in connection with the Property) and the
                     rents
<PAGE>

                   which would have been payable under the Lease had such
                   disclaimer not occurred in both cases for the period
                   beginning on the date of such disclaimer and ending on
                   whichever is the earlier of:

                   15.1.4.1  the date six months after the disclaimer

                   15.1.4.2  the end or sooner determination of the Tenancy

          15.1.5.  The Guarantor further covenants and guarantees the
                   obligations of the Tenant under any authorised guarantee
                   agreement entered into by the Tenant under the terms of this
                   Lease

EXECUTED BY THE PARTIES AS A DEED and delivered on but not before the date
inserted as the date of this Lease

                                FIRST SCHEDULE

                    Form of authorised guarantee agreement

1.   In consideration of the Landlord agreeing to the assignment of the Lease
     the Tenant covenants and guarantees with and to the Landlord as a primary
     obligation that with effect from the date of the assignment:

     1.1. The Assignee will punctually pay the rents and perform and observe the
          covenants and other terms of the Lease

     1.2. If the Assignee does not pay all or part of the rents or does not
          perform and observe any or all of the covenants or other terms of the
          Lease the Tenant will pay the rents and perform and observe the
          covenants or terms in respect of which the Assignee is in default
          and the Tenant will make good to the Landlord on demand and indemnify
          the Landlord against all losses damages costs and expenses arising or
          incurred by the Landlord as a result of such non-payment non-
          performance or non-observance

2.   The Tenant's liability under this Agreement will not end or be reduced
     because:

     2.1. of any time or indulgence granted by the Landlord to the Assignee or
          any neglect or forbearance of the Landlord in enforcing the payment of
          the rents or the observance or performance of the covenants or other
          terms of the Lease

     2.2. the terms of the Lease have been varied by agreement between the
          parties (but this is subject to the provisions of Section 18 of the
          Landlord and Tenant (Covenants) Act 1995)
<PAGE>

     2.3. the Assignee has surrendered part of the Property in which case the
          liability of the Tenant under this agreement will continue in respect
          of the part of the Property which has not been surrendered after
          making any necessary apportionments under Section 140 of the Law of
          Property Act 1925

     2.4. of any other act or thing by which the Tenant would have been released
          if it were not for this provision

3.   The Tenant further covenants with the Landlord that if the Lease is
     disclaimed before any lawful assignment of it by the Assignee:

     3.1. the Landlord may within six months after that disclaimer require the
          Tenant to accept a new lease of the Property for a term equivalent to
          the residue which if there had been no disclaimer would have remained
          of the Tenancy at the same rent and subject to the same covenants and
          conditions as are payable under and applicable to the Tenancy
          immediately before the date of the disclaimer

     3.2. such new lease and the rights and liabilities under it will take
          effect from the date of the disclaimer

     3.3. 3. the new lease and the Tenant will accept the new lease accordingly
          and will execute and deliver to the Landlord a counterpart of it

4.   If the Lease is disclaimed and for any reason the Landlord does not require
     the Tenant to accept a new lease of the Property under paragraph 3 the
     Tenant will pay to the Landlord on demand an amount equal to the difference
     between any money received by the Landlord for the use or occupation of the
     Property (less any expenditure incurred by the Landlord in connection with
     the Property) and the rents which would have been payable under the Lease
     had such disclaimer not occurred in both cases for the period beginning on
     the date of such disclaimer and ending on whichever is the earlier of:

     4.1. the date six months after such disclaimer

     4.2. the end or sooner determination of the Tenancy

5.   Nothing in this agreement requires the Tenant to guarantee in any way the
     liability for the covenants and other terms of the Lease of any person
     other than the Assignee

6.   Nothing in this agreement will make the Tenant subject to any liability
     restriction or other requirement (of any kind) in relation to any time
     after the Assignee is by law released from the covenants and other terms of
     the Lease

7.   Words and expressions used in this agreement shall have the same meaning as
     in the Lease
<PAGE>

                                SECOND SCHEDULE

                          Form of guarantee covenant

1.   In consideration of the Landlord agreeing to the assignment of the Lease
     the Guarantor covenants and guarantees with and to the Landlord as a
     primary obligation that with effect from the date of the assignment:

     1.1. The Tenant will punctually pay the rents and perform and observe the
          covenants and other terms of the Lease

     1.2. If the Tenant does not pay all or part of the rents or does not
          perform and observe any or all of the covenants or other terms of the
          Lease the Guarantor will pay the rents and perform and observe the
          covenants or terms in respect of which the Tenant is in default and
          the Guarantor will make good to the Landlord on demand and indemnify
          the Landlord against all losses damages costs and expenses arising or
          incurred by the Landlord as a result of such non-payment non-
          performance or non-observance

2.   The Guarantor's liability under this Agreement will not be reduced or ended
     because:

     2.1. of any time or indulgence granted by the Landlord to the Tenant or any
          neglect or forbearance of the Landlord in enforcing the payment of the
          rents or the observance or performance of the covenants or other terms
          of the Lease

     2.2. the terms of the Lease have been varied by agreement between the
          parties (but this is subject to the provisions of Section 18 of the
          Landlord and Tenant (Covenants) Act 1995)

     2.3. the Tenant has surrendered part of the Property in which case the
          liability of the Guarantor under this agreement will continue in
          respect of the part of the Property which has not been surrendered
          after making any necessary apportionments under Section 140 of the Law
          of Property Act 1925

     2.4. of any other act or thing by which the Guarantor would have been
          released if it were not for this provision

3.   The Guarantor further covenants with the Landlord that if the Lease is
     disclaimed before any lawful assignment of it by the Tenant:

     3.1. the Landlord may within six months after that disclaimer require the
          Guarantor to accept a new lease of the Property for a term equivalent
          to the residue which if there had been no disclaimer would have
          remained of the Tenancy at the same rent and subject to the same
<PAGE>

          covenants and conditions as were payable under and applicable to the
          Tenancy immediately before the date of the disclaimer

     3.2. such new lease and the rights and liabilities under it will take
          effect from the date of the disclaimer

     3.3. the Guarantor will pay the Landlord's costs incurred in connection
          with the new lease and the Guarantor will accept the new lease
          accordingly and will execute and deliver to the Landlord a counterpart
          of it

4.   If the Lease is disclaimed and for any reason the Landlord does not require
     the Guarantor to accept a new lease of the Property under paragraph 3 the
     Guarantor will pay to the Landlord on demand an amount equal to the
     difference between any money received by the Landlord for the use or
     occupation of the Property (less any expenditure incurred by the Landlord
     in connection with the Property) and the rents which would have been
     payable under the Lease had such disclaimer not occurred in both cases for
     the period beginning on the date of the disclaimer and ending on whichever
     is the earlier of:

     4.1. the date six months after the disclaimer

     4.2. the end or sooner determination of the Tenancy

5.   The Guarantor further covenants and guarantees the obligations of the
     Tenant under any authorised guarantee agreement entered into by the Tenant
     under the terms of the Lease

6.   For the purpose of these guarantee provisions references to the Tenant are
     to the Tenant in relation to whom the Guarantor's guarantee is given but
     not to any lawful assignee of such Tenant

7.   Words and expressions used in this Agreement have the same meaning as in
     the Lease
<PAGE>

EXECUTED as a Deed by of         )                                    [SEAL]
ADAPTIVE BROADBAND LIMITED       )
by the signatures of:            )


     /s/ [ILLEGIBLE]             Director
     ---------------------

     /s/ [ILLEGIBLE]             Secretary
     ---------------------
     for and on behalf of
      PPTSEC Ltd.

THE COMMON SEAL of               )                                    [SEAL]
ADAPTIVE BROADBAND               )
CORPORATION was affixed in the   )
presence of:-                    )

     /s/ [ILLEGIBLE]            Executive Vice President and Chief
     -------------------         Financial Officer



    /s/  [ILLGIBLE]
    --------------------         Secretary