CONFORMED COPY
To:          Huntingdon Life Sciences Group plc
             Huntingdon Life Sciences Limited and
             c/o Woolley Road
             Alconbury
             Huntingdon
             Cambridgeshire PE17 5HS


                                                         7 August 1998



Dear Sirs,

Bridging  Facility to be made  available by National  Westminster  Bank Plc (the
"Overdraft  Bank") in  favour of (1)  Huntingdon  Life  Sciences  Group plc (the
"Parent")  and (2)  Huntingdon  Life  Sciences  Limited  ("HLSL")  (together the
"Borrowers")

National  Westminster  Bank Plc in its  capacity  as  Overdraft  Bank under this
Letter is  pleased  to advise  you that  with the  authority  of the Banks it is
prepared to offer the Borrowers the bridging facility referred to in Paragraph 2
of this Letter (the "Bridging  Facility") on the terms and conditions  contained
herein.

1.           DEFINITIONS AND INTERPRETATION

1.1          Definitions

             In this Letter  capitalised  expressions  shall,  unless  otherwise
             defined,  have the same  meanings  given to them in the  Facilities
             Agreement  and the following  expressions  shall have the following
             meanings:

             "Business Day" means a day (other than a Saturday) on which banks
             are open in the City of London for the transaction of Business;

             "Circular" means the circular to be issued by the Parent relating
             to the Placings;

             "DKB" means Dresdner Kleinwort Benson;

             "Existing  Overdraft  Facilities"  means the overdraft  facility of
             (pound)5,000,000  made  available to the Borrowers by the Overdraft
             Bank  pursuant  to the  terms of the  Original  Overdraft  Facility
             Letter and the Second Overdraft Facility Letter;

             "Expiry Date" means 2 September 1998 or such other date as the
             parties hereto may agree;

             "Facilities  Agreement"  means the facilities  agreement  dated 1st
             November  1995  between  the  Borrowers,  the  Banks  and  National
             Westminster  Bank Plc as agent as  amended  by a letter  dated 21st
             November  1995,  by  the  Original  Overdraft  Letter  and  by  the
             Amendment Agreement;

             "Intercreditor  Agreement" means the fourth intercreditor agreement
             to be entered into by each of the  Borrowers,  the Overdraft  Bank,
             the Agent and the Banks to record  the  priority  of the  Overdraft
             Bank with respect to the amounts  loaned to the  Borrowers by means
             of the Bridging Facility;.

             "Investor Placing" means the raising by the Parent of new equity by
             means  of a  subscription  by  certain  investors  for  120,000,000
             ordinary  shares  of 5 pence  each in the  Parent in order to raise
             (pound)15,000,000 (gross);

             "Investor  Placing  Agreement"  means  the  agreement  of even date
             herewith  between  the Parent  and the  investors  documenting  the
             Investor Placing;

             "New Facilities Agreement" means the New Facilities Agreement of
             even date herewith between National Westminster Bank Plc as Agent,
             the Banks and the Borrowers;

             "Original Overdraft Letter" means the letter dated 26th February
             1998 from the Overdraft Bank to the Borrowers;

             "Placings" mean the Investor Placing and the Shareholder Placing;

             "Resolutions" mean the resolutions of the shareholders of the
             Parent set out in the notice of EGM which is to be sent out with
             the Circular;

             "Second Overdraft  Facility letter" means the facility letter dated
             17th March 1998 from the Overdraft Bank to the Borrowers;

             "Shareholder Placing" means the raising by the Parent of new equity
             by means of a placing and open offer of 57,003,431  ordinary shares
             of 5 pence  each in the  Parent  in order to  raise  not less  than
             (pound)7,000,000 (gross);

             "Shareholder  Placing  Agreement"  means the agreement of even date
             herewith  between the Parent and DKB  relating  to the  Shareholder
             Placing;

             "Transaction  Proceeds"  means the monies (net of costs)  raised by
             the Parent pursuant to the Placings.


1.2          Interpretation

             In this Letter, unless the context otherwise requires:

             (a)         references to any persons shall be construed so as to
                         include that person's assigns, transferees or
                         successors in title;

             (b)         references to any document (or any specified provisions
                         of any  document)  shall be construed as  references to
                         such  document or that  provision as amended or novated
                         or supplemented  or replaced,  as the case may be, from
                         time to time;

             (c)         references to the singular shall include the plural and
                         vice  versa and  references  by way of male,  female or
                         neuter pronoun shall include references to all genders;
                         and

             (d)         references  to  paragraphs   are  to  be  construed  as
                         references to the  paragraphs of this Letter as amended
                         or varied from time to time.

2.           BRIDGING FACILITY

2.1          Subject to Paragraph 4 the Overdraft  Bank agrees to make available
             to the  Borrowers  from  the  date  of  this  letter  an  aggregate
             principal amount of  (pound)1,000,000  by way of sterling overdraft
             on the Borrowers' current accounts with the Overdraft Bank.

2.2          No drawing  shall be made under the  Bridging  Facility  unless the
             existing Overdraft Facilities are drawn down in full at the time of
             such drawing.

2.3          The Bridging Facility is in addition to the Existing Overdraft
             Facilities.

3.           PURPOSE

             The Borrowers shall utilise the Bridging  Facility for the purposes
             of their general corporate purposes.

4.           CONDITIONS PRECEDENT TO THE BRIDGING FACILITY

             The Bridging Facility shall be made available to the Borrowers when
             the Overdraft Bank has received the following in form and substance
             satisfactory to it:

(a)          the enclosed copy of this Letter with the endorsed acceptance duly
             signed on
                         behalf of each of the Borrowers;

(b)                      copies,   each  certified  to  be  true,  complete  and
                         up-to-date  copies,  of  resolutions  of  each  of  the
                         relevant Borrower's boards of directors authorising the
                         acceptance  and  execution  of  this  Letter,  the  New
                         Facilities  Agreement and the  Intercreditor  Agreement
                         and unanimously supporting,  approving and recommending
                         the Placings to the shareholders of the Parent;

(c)                      the   Intercreditor   Agreement,   the  New  Facilities
                         Agreement,  the  Investor  Placing  Agreement  and  the
                         Shareholder  Placing  Agreement  duly  executed  by the
                         parties thereto;

(d)          a certified copy of the Circular;

             (e)         a copy of the most up to date financial model of the
                         Investors for the Group; and

             (f)         a certified  copy of a letter  addressed  to the Parent
                         and/  or  DKB  from  N M  Rothschilds  &  Sons  Limited
                         confirming  the terms on which  they hold funds for the
                         purpose of meeting the Investors  obligations under the
                         Investor Placing Agreement.

5.           REPAYMENT ON DEMAND

             The Overdraft  Bank may with the prior  written  consent of all the
             Banks  terminate  the Bridging  Facility at any time in  accordance
             with Clause 13.3 of the New  Facilities  Agreement  and make demand
             for repayment of all sums (including  accrued interest) owing under
             the Bridging Facility. In any event, the Bridging Facility shall be
             repaid from the Transaction Proceeds.


6.           GENERAL TERMS IN RELATION TO THE BRIDGING FACILITY

6.1          Interest

6.1.1        Amount

             Interest  shall accrue and be  calculated  in respect of the amount
             outstanding  under the Bridging Facility on the basis of the number
             of days  elapsed  and a 365-day  year,  at a rate equal to the base
             rate of the Overdraft Bank from time to time plus 3.0 per cent. per
             annum.

6.1.2        Default interest

             Interest  on any sum  payable in respect of the  Bridging  Facility
             which is not paid when due shall be  charged  at 4.0 per cent.  per
             annum above the Overdraft Bank's base rate from time to time.

6.1.3        Payment of interest

             Interest  calculated in accordance  with  Paragraph  6.1.1 shall be
             payable  in  arrears  and  shall  be paid by the  Borrowers  to the
             Overdraft  Bank  on the  expiry  or  termination  of  the  Bridging
             Facility.  Default interest calculated in accordance with Paragraph
             6.1.2 shall be payable (both before and after  judgment) in arrears
             and shall be  debited  to the  Parent's  current  account  with the
             Overdraft Bank and compounded on the usual monthly charging days of
             the Overdraft Bank.

6.1.4        Determination of interest

             The  statement  of the  Overdraft  Bank as to the rate or amount of
             interest  payable  pursuant  to any  provision  of this  Letter  in
             respect of the Bridging Facility shall be conclusive in the absence
             of manifest error.

6.2          Further Assurance

             The Borrowers each  undertake to perform,  execute and deliver such
             documents as the Overdraft Bank may reasonably require to implement
             the purposes of and perfect the Bridging Facility,  any security or
             any of the transactions contemplated by this Letter.

6.3.         Payments

6.3.1        No withholdings

             All payments by the Borrowers under the Bridging Facility are to be
             made in immediately  available  funds free and clear of and without
             any  withholding  or  deduction  for any and all  present or future
             taxes,  duties,  levies,  fees or other  charges  and  without  any
             set-off or counter-claim whatsoever.

6.3.2        Grossing-up

             If any deduction or  withholding  is required in respect of any sum
             payable under the Bridging  Facility,  the Borrowers shall increase
             the sum so that the net amount received by the Overdraft Bank after
             the deduction or  withholding  (and after the payment of any tax or
             additional tax which is due as a consequence of the increase) shall
             be equal to the  amount  which the  Overdraft  Bank would have been
             entitled to receive in the absence of any  requirement to make that
             deduction or withholding.

6.3.3        Authority to debit account

             The Borrowers  irrevocably  authorise  the Overdraft  Bank to debit
             from time to time to any  account the  Borrowers  may have with the
             Overdraft  Bank all or any  amounts  due to the  Overdraft  Bank in
             connection with the Bridging Facility.

6.4.         Set-off

             Each of the Borrowers authorise the Overdraft Bank:

             (a)         to apply any credit balance on any of its accounts with
                         any of the Banks (by set-off, combination or otherwise)
                         in  satisfaction  of any sum due and payable and unpaid
                         in relation to the Bridging Facility or otherwise under
                         this Letter; and

             (b)         to purchase  with the moneys  standing to the credit of
                         any  such  account  such  other  currencies  as  may be
                         necessary to effect such application.

6.5          Joint and Several Liability

             The obligations of each of the Borrowers to the Overdraft Bank, the
             Agent and the Banks under this Letter shall be joint and several.

7.           UNDERTAKINGS TO THE BANKS

7.1     The Borrowers undertake with the Overdraft Bank, and the Banks that:

             (a)      they will  continue  to  provide  the  Banks  with such
                      further  financial  information,  documents and records
                      about the financial condition, operations and prospects
                      of  the  Group  as the  Agent  may  reasonably  require
                      including   individual   profit  and  loss  statements,
                      balance  sheets and Cash Flow  Forecasts  in respect of
                      each Borrower as requested;

             (b)      they will use their best  endeavours  provide the Banks
                      with such  information  in respect of the Investors and
                      the Investor Placing as the Agent  reasonably  requires
                      and keep the Agent  informed  of the  timetable  of the
                      Investor Placing and any changes to that timetable;

             (c)      they will  provide the Banks with such  information  as
                      the  Agent  reasonably   requires  in  respect  of  the
                      Shareholder Placing.

8.           COSTS

             The Borrowers agree and undertake that they will be responsible for
             and will pay on demand on a full  indemnity  basis all  proper  and
             reasonable  costs,  charges and expenses incurred by the Banks, the
             Agent and/or the Overdraft Bank in connection  with this Letter and
             the matters  contemplated  hereunder  including without  limitation
             reasonable legal fees.

9.           SUCCESSORS

             The  agreement  evidenced by this Letter shall enure to the benefit
             of the Overdraft Bank, the Agent and the Banks and their successors
             and  permitted  assigns  from  time  to  time  including,   without
             limitation,  any entity with which the Overdraft Bank, the Agent or
             the Banks may merge or  amalgamate or by which they may be absorbed
             or to which they may transfer all or any part of their  undertaking
             or  assets,  and  any  change  in  the  constitution  of any of the
             Overdraft  Bank,  the  Agent  or  the  Banks  or any  such  merger,
             amalgamation,  absorption or transfer shall not prejudice or affect
             any of their rights  under this Letter in any respect.  Neither the
             Overdraft  Bank nor the  Borrowers  may assign or  transfer  any of
             their rights, benefits or obligations under this Letter.

10.          DEMAND OR NOTICE

             Any demand or notice on any of the  Borrowers  under this Letter in
             relation to the Bridging  Facility  shall be made in writing signed
             by an officer of the  Overdraft  Bank and served either by personal
             delivery on any officer of the Borrowers at any place or by post or
             by hand delivery addressed to its registered office or its place of
             business last known to the Overdraft  Bank or by facsimile or telex
             using the relevant number last known to the Overdraft Bank. Service
             by post on the  Borrowers  shall be deemed to be  effective  on the
             next  business  day after the date of posting  and  notwithstanding
             that it be returned  undelivered.  Service by facsimile or telex on
             the  Borrowers  shall be deemed to be effective  on  despatch.  Any
             notice to the Overdraft Bank,  under this Letter in relation to the
             Bridging  Facility shall be made to the Overdraft  Bank's branch at
             the address stated at the head of this Letter or such other address
             as may be notified by the Overdraft Bank from time to time.

11.          SEVERANCE

             If at any time any provision of this Letter is or becomes  invalid,
             illegal  or  unenforceable  in any  respect  under  any  law of any
             jurisdiction,  the  validity,  legality and  enforceability  of the
             remaining provisions of this Letter and the validity,  legality and
             enforceability   of  those   provisions  under  the  law  of  other
             jurisdictions shall not in any way be affected or impaired thereby.

12.          PROPER LAW

             This Letter shall be governed by and construed in  accordance  with
             the laws of England and the Borrowers  submit to the  non-exclusive
             jurisdiction of the English courts.

13.          PERIOD OF OFFER

             The  Borrowers  must  confirm  their  acceptance  of the  terms and
             conditions  contained in this Letter by signing the  acceptance  on
             the  enclosed  duplicate  of this  Letter and  returning  it to the
             Overdraft Bank together with the documents  signed by the Borrowers
             referred to in  Paragraph  4 within 2 Business  Days of the date of
             this Letter.  If this offer is not so accepted  within that period,
             it shall lapse.

Yours faithfully


S.J. HAMILTON

 ......................................
for and on behalf of
NATIONAL WESTMINSTER BANK PLC
(as Overdraft Bank)



CHRISTOPHER CLIFFE

 ................................................
Signed by Director
for and on behalf of
HUNTINGDON LIFE SCIENCES GROUP PLC
duly authorised by a board resolution dated 6 August 1998


We acknowledge  receipt of the  original of this Letter  dated 7 August 1998 of
which this is a true copy and accept the terms and conditions thereof.


CHRISTOPHER CLIFFE

 ................................................
Signed by Director
for and on behalf of
HUNTINGDON LIFE SCIENCES LIMITED
duly authorised by a board resolution dated 6 August 1998


We  acknowledge  receipt of the original of this Letter dated 7 August 1998 of
which this is a true copy and accept the terms and conditions thereof.