Document:

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                                                                  EXHIBIT 10.1.5

                               BIOVEX GROUP, INC.

                           RESTRICTED STOCK AGREEMENT
                                FOR US EMPLOYEES
                     GRANTED UNDER 2005 STOCK INCENTIVE PLAN

     AGREEMENT made this 30th day of August, 2005, between BioVex Group, Inc, a
Delaware corporation (the "Company"), and Stephen Gorgol (the "Participant").

     For valuable consideration, receipt of which is acknowledged, the parties
hereto agree as follows:

     1.   Purchase of Shares.

     The Company shall issue and sell to the Participant, and the Participant
shall purchase from the Company, subject to the terms and conditions set forth
in this Agreement and in the Company's 2005 Stock Incentive Plan (the "Plan"),
135,000 shares (the "Shares") of common stock, $0.0001 par value, of the Company
("Common Stock"), at a purchase price of $0.0001 per share. The aggregate
purchase price for the Shares shall be paid by the Participant by check payable
to the order of the Company or such other method as may be acceptable to the
Company. Upon receipt by the Company of payment for the Shares, the Company
shall issue to the Participant one or more certificates in the name of the
Participant for that number of Shares purchased by the Participant. The
Participant agrees that the Shares shall be subject to the purchase option set
forth in Section 2 of this Agreement and the restrictions on transfer set forth
in Section 4 of this Agreement.

     2.   Purchase Option.

          (a) In the event that the Participant ceases to be employed by the
Company for any reason or no reason, with or without cause, prior to the later
of the date on which a Listing (as defined in the Plan) takes effect and
_______, 200_,(1) the Company shall have the right and option (the "Purchase
Option") to purchase from the Participant, for a sum of $0.0001 per share (the
"Option Price"), some or all of the Unvested Shares (as defined below).

     "Unvested Shares" means the total number of Shares multiplied by the
Applicable Percentage at the time the Purchase Option becomes exercisable by the
Company. The "Applicable Percentage" shall be (i) 100% at all times prior to a
Listing taking effect or (ii) if a Listing has taken effect shall be (1) 100%
during the 12-month period ending ____________, 200_, (2) [75%] less [2.08%] for
each month of employment completed by the Participant with the Company from and
after _________, 200_, and (3) 0% on or after ________, 200__ provided always
that, if after a Listing has taken effect but before _________, 200_, the
Participant is discharged by the Company for "cause" (as defined below), the
Applicable Percentage shall be 100%. "CAUSE" shall mean willful misconduct by
the Participant or willful failure by the

----------
(1)  Date of end of time based vesting. Thus after listing and this date, shares
     are held absolutely, even if then leave for cause.

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Participant to perform his or her responsibilities to the Company (including,
without limitation, any material breach by the Participant of any provision of
any employment, consulting, advisory, nondisclosure, non-competition or other
similar agreement between the Participant and the Company), as determined by the
Company, which determination shall be conclusive. The Participant shall be
considered to have been discharged for "Cause" if the Company determines, within
30 days after the Participant's resignation, that discharge for cause was
warranted.

          (b) For purposes of this Agreement, the Participant's employment with
the Company shall not be considered to have terminated if he or she remains
employed by a parent or subsidiary of the Company.

     3.   Exercise of Purchase Option and Closing.

          (a) The Company may exercise the Purchase Option by delivering or
mailing to the Participant (or his estate), within 90 days after the termination
of the employment of the Participant with the Company, a written notice of
exercise of the Purchase Option. Such notice shall specify the number of Shares
to be purchased. If and to the extent the Purchase Option is not so exercised by
the giving of such a notice within such 90-day period, the Purchase Option shall
automatically expire and terminate effective upon the expiration of such 90-day
period.

          (b) Within 10 days after delivery to the Participant of the Company's
notice of the exercise of the Purchase Option pursuant to subsection (a) above,
the Participant (or his estate) shall, pursuant to the provisions of the Joint
Escrow Instructions referred to in Section 6 below, tender to the Company at its
principal offices the certificate or certificates representing the Shares which
the Company has elected to purchase in accordance with the terms of this
Agreement, duly endorsed in blank or with duly endorsed stock powers attached
thereto, all in form suitable for the transfer of such Shares to the Company.
Promptly following its receipt of such certificate or certificates, the Company
shall pay to the Participant the aggregate Option Price for such Shares
(provided that any delay in making such payment shall not invalidate the
Company's exercise of the Purchase Option with respect to such Shares).

          (c) After the time at which any Shares are required to be delivered to
the Company for transfer to the Company pursuant to subsection (b) above, the
Company shall not pay any dividend to the Participant on account of such Shares
or permit the Participant to exercise any of the privileges or rights of a
stockholder with respect to such Shares, but shall, in so far as permitted by
law, treat the Company as the owner of such Shares.

          (d) The Option Price may be payable, at the option of the Company, in
cancellation of all or a portion of any outstanding indebtedness of the
Participant to the Company or in cash (by check) or both.

          (e) The Company shall not purchase any fraction of a Share upon
exercise of the Purchase Option, and any fraction of a Share resulting from a
computation made pursuant to Section 2 of this Agreement shall be rounded to the
nearest whole Share (with any one-half Share being rounded upward).

          (f) The Company may assign its Purchase Option to one or more persons
or entities.

                                       -2-

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     4.   Restrictions on Transfer.

     The Participant shall not sell, assign, transfer, pledge, hypothecate or
otherwise dispose of, by operation of law or otherwise (collectively "transfer")
any Shares, or any interest therein, that are subject to the Purchase Option,
except that the Participant may transfer such Shares (i) to or for the benefit
of any spouse, children, parents, uncles, aunts, siblings, grandchildren and any
other relatives approved by the Board of Directors (collectively, "Approved
Relatives") or to a trust established solely for the benefit of the Participant
and/or Approved Relatives, provided that such Shares shall remain subject to
this Agreement (including without limitation the restrictions on transfer set
forth in this Section 4 and the Purchase Option) and such permitted transferee
shall, as a condition to such transfer, deliver to the Company a written
instrument confirming that such transferee shall be bound by all of the terms
and conditions of this Agreement or (ii) as part of the sale of all or
substantially all of the shares of capital stock of the Company (including
pursuant to a merger or consolidation), provided that, in accordance with the
Plan, the securities or other property received by the Participant in connection
with such transaction shall remain subject to this Agreement.

     5.   Stockholders' Agreement

     The Participant shall, upon execution of this Agreement, become a party to,
and be bound as a "Common Holder" under, the Company's Stockholders' Agreement,
dated as of 30 August 2005 and as amended or substituted from time to time, by
executing a counterpart signature page in substantially the form of Exhibit A.

     6.   Escrow.

     The Participant shall, upon the execution of this Agreement, execute Joint
Escrow Instructions in the form attached to this Agreement as Exhibit B. The
Joint Escrow Instructions shall be delivered to the Secretary of the Company, as
escrow agent thereunder. The Participant shall deliver to such escrow agent a
stock assignment duly endorsed in blank, in the form attached to this Agreement
as Exhibit C, and hereby instructs the Company to deliver to such escrow agent,
on behalf of the Participant, the certificate(s) evidencing the Shares issued
hereunder. Such materials shall be held by such escrow agent pursuant to the
terms of such Joint Escrow Instructions.

     7.   Restrictive Legends.

     All certificates representing Shares shall have affixed thereto legends in
substantially the following form, in addition to any other legends that may be
required under federal or state securities laws:

          "The shares of stock represented by this certificate are subject to
          restrictions on transfer and an option to purchase set forth in a
          certain Restricted Stock Agreement between the corporation and the
          registered owner of these shares (or his predecessor in interest), and
          such Agreement is available for inspection without charge at the
          office of the Secretary of the corporation."

                                       -3-

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          "The shares represented by this certificate have not been registered
          under the Securities Act of 1933, as amended, and may not be sold,
          transferred or otherwise disposed of in the absence of an effective
          registration statement under such Act or an opinion of counsel
          satisfactory to the corporation to the effect that such registration
          is not required."

     8.   Provisions of the Plan.

     This Agreement is subject to the provisions of the Plan, a copy of which is
furnished to the Participant with this Agreement.

     9.   Investment Representations.

     The Participant represents, warrants and covenants as follows:

          (a) The Participant is purchasing the Shares for his own account for
investment only, and not with a view to, or for sale in connection with, any
distribution of the Shares in violation of the Securities Act of 1933 (the
"Securities Act"), or any rule or regulation under the Securities Act.

          (b) The Participant has had such opportunity as he has deemed adequate
to obtain from representatives of the Company such information as is necessary
to permit him to evaluate the merits and risks of his investment in the Company.

          (c) The Participant has sufficient experience in business, financial
and investment matters to be able to evaluate the risks involved in the purchase
of the Shares and to make an informed investment decision with respect to such
purchase.

          (d) The Participant can afford a complete loss of the value of the
Shares and is able to bear the economic risk of holding such Shares for an
indefinite period.

          (e) The Participant understands that (i) the Shares have not been
registered under the Securities Act and are "restricted securities" within the
meaning of Rule 144 under the Securities Act; (ii) the Shares cannot be sold,
transferred or otherwise disposed of unless they are subsequently registered
under the Securities Act or an exemption from registration is then available;
(iii) in any event, the exemption from registration under Rule 144 will not be
available for at least one year and even then will not be available unless a
public market then exists for the Common Stock, adequate information concerning
the Company is then available to the public, and other terms and conditions of
Rule 144 are complied with; and (iv) there is now no registration statement on
file with the Securities and Exchange Commission with respect to any stock of
the Company and the Company has no obligation or current intention to register
the Shares under the Securities Act.

     10.  Withholding Taxes; Section 83(b) Election etc.

          (a) The Participant acknowledges and agrees that the Company has the
right to deduct from payments of any kind otherwise due to the Participant any
federal, state or local

                                       -4-

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taxes or social security of any kind (whether US or otherwise) (together
"Taxes") required by law to be withheld or paid on behalf of or in respect of
the Participant with respect to the purchase of the Shares by the Participant or
the lapse of the Purchase Option.

          (b) The Participant has reviewed with the Participant's own tax
advisors the federal, state, local and foreign tax consequences of this
investment and the transactions contemplated by this Agreement. The Participant
is relying solely on such advisors and not on any statements or representations
of the Company or any of its agents. The Participant understands that the
Participant (and not the Company) shall be responsible for the Participant's own
tax liability that may arise as a result of this investment or the transactions
contemplated by this Agreement. The Participant understands that it may be
beneficial in many circumstances to elect to be taxed at the time the Shares are
purchased rather than when and as the Company's Purchase Option expires by
filing an election under Section 83(b) of the Internal Revenue Code of 1986 with
the I.R.S. within 30 days from the date of purchase.(2)

          THE PARTICIPANT ACKNOWLEDGES THAT IT IS THE PARTICIPANT'S SOLE
RESPONSIBILITY AND NOT THE COMPANY'S TO FILE TIMELY THE ELECTION UNDER SECTION
83(b), EVEN IF THE PARTICIPANT REQUESTS THE COMPANY OR ITS REPRESENTATIVES TO
MAKE THIS FILING ON THE PARTICIPANT'S BEHALF.

     11.  Miscellaneous.

          (a) No Rights to Employment. The Participant acknowledges and agrees
that the vesting of the Shares pursuant to Section 2 hereof is earned only by
continuing service as an employee at the will of the Company (not through the
act of being hired or purchasing shares hereunder). The Participant further
acknowledges and agrees that the transactions contemplated hereunder and the
vesting schedule set forth herein do not constitute an express or implied
promise of continued engagement as an employee or consultant for the vesting
period, for any period, or at all.

          (b) Severability. The invalidity or unenforceability of any provision
of this Agreement shall not affect the validity or enforceability of any other
provision of this Agreement, and each other provision of this Agreement shall be
severable and enforceable to the extent permitted by law.

          (c) Waiver. Any provision for the benefit of the Company contained in
this Agreement may be waived, either generally or in any particular instance, by
the Board of Directors of the Company.

          (d) Binding Effect. This Agreement shall be binding upon and inure to
the benefit of the Company and the Participant and their respective heirs,
executors, administrators, legal representatives, successors and assigns,
subject to the restrictions on transfer set forth in Sections 4 and 5 of this
Agreement.

----------
(2)  If the Shares are sold to the Participant for a purchase price equal to
     their fair market value at the time of such sale, a Section 83(b) election
     will almost always be advisable.

                                       -5-

<PAGE>

          (e) Notice. All notices required or permitted hereunder shall be in
writing and deemed effectively given upon personal delivery or five days after
deposit in the United States Post Office, by registered or certified mail,
postage prepaid, addressed to the other party hereto at the address shown
beneath his or its respective signature to this Agreement, or at such other
address or addresses as either party shall designate to the other in accordance
with this Section 12(e).

          (f) Pronouns. Whenever the context may require, any pronouns used in
this Agreement shall include the corresponding masculine, feminine or neuter
forms, and the singular form of nouns and pronouns shall include the plural, and
vice versa.

          (g) Entire Agreement. This Agreement and the Plan constitute the
entire agreement between the parties, and supersedes all prior agreements and
understandings, relating to the subject matter of this Agreement.

          (h) Amendment. This Agreement may be amended or modified only by a
written instrument executed by both the Company and the Participant.

          (i) Governing Law. This Agreement shall be construed, interpreted and
enforced in accordance with the internal laws of the State of Delaware without
regard to any applicable conflicts of laws.

          (j) Participant's Acknowledgments. The Participant acknowledges that
he or she: (i) has read this Agreement; (ii) has been represented in the
preparation, negotiation, and execution of this Agreement by legal counsel of
the Participant's own choice or has voluntarily declined to seek such counsel;
(iii) understands the terms and consequences of this Agreement; (iv) is fully
aware of the legal and binding effect of this Agreement; and (v) understands
that the law firm of Wilmer Cutler Pickering Hale and Dorr LLP, is acting as
counsel to the Company in connection with the transactions contemplated by the
Agreement, and is not acting as counsel for the Participant.

     IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the day and year first above written.

                                        BIOVEX GROUP, INC.

                                        By: /s/ Philip Astley-Sparke
                                            ------------------------------------
                                        Title: President
                                        Address: 8 Amanda Lane
                                                 Weston, MA 02493

                                        /s/ Stephen Gorgol
                                        ----------------------------------------
                                        Stephen Gorgol
                                        Address: 5 Blackthorne Circle
                                                 Hopkinton, MA 01748

                                       -6-

<PAGE>

                                    EXHIBIT A

                               BIOVEX GROUP, INC.

                           COUNTERPART SIGNATURE PAGE

     The undersigned, a holder of common stock of BioVex Group, Inc., a Delaware
corporation (the "Company"), hereby agrees to become a party to, and to be bound
as a "Common Holder" under the Company's Stockholders' Agreement, originally
entered into among the Company and certain of its stockholders as of 30 August
2005, a copy of which is attached hereto as Annex A.

     EXECUTED as of __________, 200[_].

                                        ----------------------------------------
                                        (Signature)

                                        (Printed Name)

                                       -7-

<PAGE>

                                    EXHIBIT B

                               BIOVEX GROUP, INC.

                            Joint Escrow Instructions

                                 August 30, 2005

Secretary
BioVex Group, Inc.

Dear Sir:

     As Escrow Agent for BioVex Group, Inc., a Delaware corporation, and its
successors in interest under the Restricted Stock Agreement (the "Agreement") of
even date herewith, to which a copy of these Joint Escrow Instructions is
attached (the "Company"), and the undersigned person ("Holder"), you are hereby
authorized and directed to hold the documents delivered to you pursuant to the
terms of the Agreement in accordance with the following instructions:

     1. Appointment. Holder irrevocably authorizes the Company to deposit with
you any certificates evidencing Shares (as defined in the Agreement) to be held
by you hereunder and any additions and substitutions to said Shares. For
purposes of these Joint Escrow Instructions, "Shares" shall be deemed to include
any additional or substitute property. Holder does hereby irrevocably constitute
and appoint you as his attorney-in-fact and agent for the term of this escrow to
execute with respect to such Shares all documents necessary or appropriate to
make such Shares negotiable and to complete any transaction herein contemplated.
Subject to the provisions of this Section 1 and the terms of the Agreement,
Holder shall exercise all rights and privileges of a stockholder of the Company
while the Shares are held by you.

     2. Closing of Purchase.

          (a) Upon any purchase by the Company of the Shares pursuant to the
Agreement, the Company shall give to Holder and you a written notice specifying
the purchase price for the Shares, as determined pursuant to the Agreement, and
the time for a closing hereunder (the "Closing") at the principal office of the
Company. Holder and the Company hereby irrevocably authorize and direct you to
close the transaction contemplated by such notice in accordance with the terms
of said notice.

          (b) At the Closing, you are directed (i) to date the stock assignment
form or forms necessary for the transfer of the Shares, (ii) to fill in on such
form or forms the number of Shares being transferred, and (iii) to deliver same,
together with the certificate or certificates

                                       -8-

<PAGE>

evidencing the Shares to be transferred, to the Company against the simultaneous
delivery to you of the purchase price for the Shares being purchased pursuant to
the Agreement.

     3. Withdrawal. The Holder shall have the right to withdraw from this escrow
any Shares as to which the Purchase Option (as defined in the Agreement) has
terminated or expired.(3)

     4. Duties of Escrow Agent.

          (a) Your duties hereunder may be altered, amended, modified or revoked
only by a writing signed by all of the parties hereto.

          (b) You shall be obligated only for the performance of such duties as
are specifically set forth herein and may rely and shall be protected in relying
or refraining from acting on any instrument reasonably believed by you to be
genuine and to have been signed or presented by the proper party or parties. You
shall not be personally liable for any act you may do or omit to do hereunder as
Escrow Agent or as attorney-in-fact of Holder while acting in good faith and in
the exercise of your own good judgment, and any act done or omitted by you
pursuant to the advice of your own attorneys shall be conclusive evidence of
such good faith.

          (c) You are hereby expressly authorized to disregard any and all
warnings given by any of the parties hereto or by any other person or entity,
excepting only orders or process of courts of law, and are hereby expressly
authorized to comply with and obey orders, judgments or decrees of any court. If
you are uncertain of any actions to be taken or instructions to be followed, you
may refuse to act in the absence of an order, judgment or decrees of a court. In
case you obey or comply with any such order, judgment or decree of any court,
you shall not be liable to any of the parties hereto or to any other person or
entity, by reason of such compliance, notwithstanding any such order, judgment
or decree being subsequently reversed, modified, annulled, set aside, vacated or
found to have been entered without jurisdiction.

          (d) You shall not be liable in any respect on account of the identity,
authority or rights of the parties executing or delivering or purporting to
execute or deliver the Agreement or any documents or papers deposited or called
for hereunder.

          (e) You shall be entitled to employ such legal counsel and other
experts as you may deem necessary properly to advise you in connection with your
obligations hereunder and may rely upon the advice of such counsel.

          (f) Your rights and responsibilities as Escrow Agent hereunder shall
terminate if (i) you cease to be Secretary of the Company or (ii) you resign by
written notice to each party. In the event of a termination under clause (i),
your successor as Secretary shall become Escrow Agent hereunder; in the event of
a termination under clause (ii), the Company shall appoint a successor Escrow
Agent hereunder.

----------
(3)  If there is a Right of First Refusal in addition to the Purchase Option,
     consideration should be given to extending the escrow to cover the period
     of time when the Right of First Refusal remains in effect.

                                       -9-

<PAGE>

          (g) If you reasonably require other or further instruments in
connection with these Joint Escrow Instructions or obligations in respect
hereto, the necessary parties hereto shall join in furnishing such instruments.

          (h) It is understood and agreed that if you believe a dispute has
arisen with respect to the delivery and/or ownership or right of possession of
the securities held by you hereunder, you are authorized and directed to retain
in your possession without liability to anyone all or any part of said
securities until such dispute shall have been settled either by mutual written
agreement of the parties concerned or by a final order, decree or judgment of a
court of competent jurisdiction after the time for appeal has expired and no
appeal has been perfected, but you shall be under no duty whatsoever to
institute or defend any such proceedings.

          (i) These Joint Escrow Instructions set forth your sole duties with
respect to any and all matters pertinent hereto and no implied duties or
obligations shall be read into these Joint Escrow Instructions against you.

          (j) The Company shall indemnify you and hold you harmless against any
and all damages, losses, liabilities, costs, and expenses, including attorneys'
fees and disbursements, (including without limitation the fees of counsel
retained pursuant to Section 4(e) above, for anything done or omitted to be done
by you as Escrow Agent in connection with this Agreement or the performance of
your duties hereunder, except such as shall result from your gross negligence or
willful misconduct.

     5. Notice. Any notice required or permitted hereunder shall be given in
writing and shall be deemed effectively given upon personal delivery or upon
deposit in the United States Post Office, by registered or certified mail with
postage and fees prepaid, addressed to each of the other parties thereunto
entitled at the following addresses, or at such other addresses as a party may
designate by ten days' advance written notice to each of the other parties
hereto.

          COMPANY:        Notices to the Company shall be sent to the
                          address set forth in the salutation hereto,
                          Attn: President

          HOLDER:         Notices to Holder shall be sent to the address
                          set forth below Holder's signature below.

          ESCROW AGENT:   Notices to the Escrow Agent shall be sent to the
                          address set forth in the salutation hereto.

     6. Miscellaneous.

          (a) By signing these Joint Escrow Instructions, you become a party
hereto only for the purpose of said Joint Escrow Instructions, and you do not
become a party to the Agreement.

                                      -10-

<PAGE>

          (b) This instrument shall be binding upon and inure to the benefit of
the parties hereto and their respective successors and permitted assigns.

                                        Very truly yours,

                                        BioVex Group, Inc.

                                        By:
                                            ------------------------------------
                                        Title:

                                        HOLDER:

                                        ----------------------------------------
                                        (Signature)

                                        Print Name

                                        Address:

                                        Date Signed:

ESCROW AGENT:

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

                                      -11-

<PAGE>

                                    EXHIBIT C

                  (STOCK ASSIGNMENT SEPARATE FROM CERTIFICATE)

     FOR VALUE RECEIVED, I hereby sell, assign and transfer unto
__________________ (_________) shares of Common Stock, $0.0001 par value per
share, of BioVex Group, Inc. (the "Corporation") standing in my name on the
books of the Corporation represented by Certificate(s) Number __________
herewith, and do hereby irrevocably constitute and appoint _____________________
attorney to transfer the said stock on the books of the Corporation with full
power of substitution in the premises.

                                        Dated:
                                               ---------------------------------

                                        Signature:
                                                   -----------------------------

     NOTICE: The signature(s) to this assignment must correspond with the name
as written upon the face of the certificate, in every particular, without
alteration, enlargement, or any change whatever and must be guaranteed by a
commercial bank, trust company or member firm of the Boston, New York or Midwest
Stock Exchange.

                                      -12-<PAGE>

                                                                 EXHIBIT 10.1.6

                                 BIOVEX LIMITED

                                   ----------

                               THE BIOVEX LIMITED
                     ENTERPRISE MANAGEMENT INCENTIVES SCHEME

                  Adopted by the Company on [31 July] 2002 and
                                amended on ____ 2003

            (Taken from the original prepared by CMS Cameron McKenna)

                                   ----------

                                  HALE AND DORR

                                  Alder Castle
                                 10 Noble Street
                                 London EC2V 7QJ
                            Tel: +44 (0)20 7645 2400
                            Fax: +44 (0)20 7645 2424
                                 Ref: 01883/002

<PAGE>

                           RULES OF THE BIOVEX LIMITED

                     ENTERPRISE MANAGEMENT INCENTIVES SCHEME

1.   DEFINITIONS

1.1  In this Scheme the words and expressions set out below shall have the
     meanings specified against them unless otherwise specifically provided and
     any reference to a provision of an Act of Parliament shall include any
     modification, consolidation, re-enactment or extension of it.

     "COMPANY" BioVex Limited (registered in England with company number
     3480520);

     "CONTROL" the meaning given to that expression by Section 840 of the Taxes
     Act;

     "DATE OF ADOPTION" the date of the adoption of this Scheme by the Company;

     "DATE OF ANNOUNCEMENT" the date on which the Company makes an announcement
     of its results for the last preceding financial year, half year or other
     period;

     "DATE OF GRANT" the date of grant of an Option as set out in the relevant
     Option Agreement;

     "DEALING DAY" a day on which the London Stock Exchange is open for the
     transaction of business;

     "DIRECTORS" the directors for the time being of the Company or the
     directors present at a duly convened meeting of the board of directors or
     of a duly appointed committee of the board of directors at which a quorum
     is present;

     "ELIGIBLE EMPLOYEE" any employee of the Company or a Qualifying Subsidiary
     who at the Date of Grant is an eligible employee within the terms of Part 4
     of Schedule 5;

     "EXERCISE CONDITION" a condition precedent to the exercise of an Option
     imposed in accordance with Rule 2.7;

     "INCOME TAX ACT" the Income Tax (Earnings and Pensions) Act 2003;

     "ISSUE OR RE-ORGANISATION" any issue of shares or other securities of the
     Company (other than as consideration for an acquisition) and/or any
     capitalisation, consolidation or sub-division or reduction of share capital
     in the Company and/or any other variation in the share capital of the
     Company which in the opinion of the Directors justifies a variation in the
     number of shares subject to Option and/or the Option Price of an Option;

     "LISTING" the admission of the shares in the Company to the Official List
     and to trading on the London Stock Exchange's market for listed securities;

<PAGE>

     "LONDON STOCK EXCHANGE" London Stock Exchange plc;

     "MARKET VALUE" such value per Share, in relation to which an Option is to
     be granted, as the Company may agree in advance in writing with the Inland
     Revenue as the market value thereof on the day preceding the relevant Date
     of Grant and determined in accordance with Part VIII of the Taxation of
     Chargeable Gains Act 1992 or if such shares have at that time been admitted
     to Listing, the average of the middle market quotations of a share as
     derived from the daily Official List on the 3 Dealing Days preceding the
     relevant Date of Grant provided that the Market Value of Shares which are
     subject to restrictions or risk of forfeiture shall be determined as if
     there were no such restrictions or risk;

     "OFFICIAL LIST" the Official List of the London Stock Exchange;

     "OPTION" a right granted to acquire Shares in the Company pursuant to the
     Scheme;

     "OPTION AGREEMENT" an agreement between the Company and an Option Holder
     executed as a Deed in accordance with Rule 2.5;

     "OPTION HOLDER" a person holding an Option or his personal representatives;

     "OPTION PRICE" the acquisition price for a Share comprised in any Option as
     determined by the Directors being not less than: (a) the Market Value of a
     Share of the class of the Company's share capital which is proposed to be
     subject to the Option; and (b) if the Shares are to be subscribed, their
     nominal value;

     "QUALIFYING COMPANY" has the meaning in Part 3 of Schedule 5;

     "QUALIFYING SUBSIDIARY" has the meaning in paragraph 11 of Schedule 5;

     "REMUNERATION COMMITTEE" the remuneration committee of the board of
     directors of the Company as from time to time constituted provided always
     that if there is no such committee "Remuneration Committee" shall mean the
     Directors;

     "RULES" these rules as amended from time to time;

     "SCHEDULE 5" Schedule 5 to the Income Tax Act;

     "SCHEME" the BioVex Limited Enterprise Management Incentives Scheme known
     as the BioVex EMI Scheme;

     "SHARES" ordinary shares in the Company which are fully paid up and are not
     redeemable, as defined in paragraph 35 of Schedule 5;

     "TAXES ACT" the Income and Corporation Taxes Act 1988.

1.2  In these Rules unless the context otherwise requires words denoting the
     singular number shall include the plural number and words denoting the
     masculine gender shall include the feminine gender.

<PAGE>

2.   PARTICIPATION

2.1  The Directors may, on such dates as they shall determine (subject to Rules
     2.2 and 2.3 below) grant Options to such Eligible Employees as they may in
     their absolute discretion select, by entering into an Option Agreement. No
     Eligible Employee shall be entitled as of right to participate in this
     Scheme. In determining the extent of participation of an Eligible Employee
     the Directors shall be subject to the limits contained in Rule 3.

2.2  Subject to Rule 2.3 below if and for so long as the shares in the Company
     are admitted to Listing or are admitted to trading on any other market
     supervised by any regulatory authority the Directors may only grant Options
     within the periods commencing:-

     2.2.1 on the fourth Dealing Day next following a Date of Announcement and
          ending 42 days after such Date of Announcement;

     2.2.2 on the date immediately preceding the day on which Listing is
          expected to take place and ending 7 days thereafter.

2.3  Notwithstanding Rule 2.2 above the Directors may grant Options outside the
     periods specified in Rule 2.2 above in circumstances which the Directors in
     their absolute discretion deem sufficiently exceptional to justify the
     grant of Options at that time.

2.4  Where Options are granted during the period specified in Rule 2.2.2 above
     and the Listing does not take place within such period the Options shall
     lapse on the day which is 30 days from the Date of Grant.

2.5  The Directors shall grant an Option by agreement with the Option Holder to
     whom it is granted. Such agreement shall be executed as a Deed by the
     Company and the Option Holder. The Option Agreement shall specify the
     number of Shares comprised in the Option, the Date of Grant, the Option
     Price, that the Option is granted pursuant to Schedule 5 and is intended to
     qualify under Schedule 5, details of any restrictions attaching to the
     Shares and details of any forfeiture provisions applying to the Shares.

2.6  Notice of the grant of an Option must be given by the Company to the Inland
     Revenue in such form as the Inland Revenue may prescribe within 92 days
     after its Date of Grant. If such Notice is not provided to the Inland
     Revenue within 92 days, the Option shall be deemed for all purposes never
     to have been granted.

2.7  The Directors may impose an Exercise Condition on any Option which they
     grant preventing its exercise unless such condition has been complied with.
     The Directors may provide that such Exercise Condition will or may be
     waived if exercise is in accordance with Clauses 4.2, 4.3 or 6 of the
     Option Agreement. If, after the Directors have imposed an Exercise
     Condition, events happen which cause them to consider that it is no longer
     appropriate they may vary the Exercise Condition provided always that any
     such amendment may only be one which the Directors reasonably consider will
     result in a fairer measure of the performance of the job of the Option
     Holder, will ensure that this Scheme operates more effectively in the
     achievement of its purpose of providing share benefits to recruit

<PAGE>

     or retain key employees of the Company and will be no more difficult to
     satisfy than would have been the case had there been no such amendment.

3.   RESTRICTIONS ON THE GRANTING OF OPTIONS

3.1  Subject to Rule 3.2, the number of shares which may be issued pursuant to
     the exercise of Options granted under this Scheme, the BioVex Limited Share
     Option Plan and any other option granted to an individual by the Company
     shall not exceed 5,709,200 (five million seven hundred and nine thousand
     two hundred) Shares, subject to any adjustment under Rule 6.

3.2  In applying the limit contained in Rule 3.1 no account will be taken of
     Shares subject to an option which, as regards any right to acquire such
     Shares, has lapsed or been released, surrendered or cancelled.

3.3  The aggregate Market Value, calculated at the Date of Grant of the Options,
     over which unexercised Options may subsist may not exceed L3,000,000 at any
     time or such other sum as shall be specified from time to time for the
     purposes of Schedule 5.

3.4  The Directors must not grant an Option to an Eligible Employee if it would
     cause the limits set out in paragraphs 5 and 6 of Schedule 5 (currently
     L100,000) or such other limit as may from time to time be specified in
     Schedule 5 to be exceeded.

3.5  No Options shall in any event be granted or otherwise offered more than 10
     years after the Date of Adoption.

4.   QUALIFYING COMPANY

The Company must be a Qualifying Company on the Date of Grant of an Option.

5.   EXERCISE OF OPTIONS

The terms on which an Option may be exercised and the procedure for exercise
shall be set out in the Option Agreement.

6.   ADJUSTMENT OF OPTIONS FOR VARIATION OF SHARE CAPITAL

6.1  Subject to Rule 6.5 below, on the occurrence of an Issue or Re-organisation
     the Directors may make such adjustment under Rule 6.2 as they consider to
     be fair and reasonable.

6.2  An adjustment made under this sub-Rule shall be to one or more of the
     following:-

     6.2.1 the number of Shares in respect of which an Option granted under this
          Scheme may be exercised;

     6.2.2 the price at which Shares may be acquired by the exercise of an
          Option;

<PAGE>

     6.2.3 where an Option has been exercised but no Shares have been allotted
          or transferred pursuant to such exercise, the number of Shares which
          may be so allotted or transferred and the price at which they may be
          acquired.

6.3  An adjustment under Rule 6.2 above may have the effect of reducing the
     price at which Shares may be acquired by the exercise of the Option to less
     than their nominal value, but, only if and to the extent that the Directors
     shall be authorised to capitalise from the reserves of the Company a sum
     equal to the amount by which the nominal value of the Shares in respect of
     which the Option is exercised and which are to be allotted pursuant to such
     exercise exceeds the price at which the same may be subscribed for and to
     apply such sum in paying up such amount on such Shares; and so that on
     exercise of the Option in respect of which such reduction shall have been
     made the Directors shall capitalise such sum (if any) and apply the same in
     paying up such amount as aforesaid.

6.4  As soon as reasonably practicable after making any adjustment under Rule
     6.2 above, the Directors shall give notice in writing thereof to all
     affected Option Holders.

7.   EXPENSES

     Any expenses of the Company involved in any issue or transfer of Shares in
     the name of an Option Holder or his personal representative(s) or
     nominee(s) shall be payable by the Company.

8.   ADMINISTRATION AND AMENDMENT

8.1  Any notification or other notice in writing which the Company is required
     to give, or may desire to give, to an Option Holder (or his personal
     representative(s)) pursuant to the Scheme or any Option Agreement shall be
     sufficiently given if delivered to him by hand or sent through the post in
     prepaid cover addressed to the Option Holder (or his personal
     representative(s)) at the last address known to the Company as being his
     address. Any certificate, notification or other notice in writing required
     to be given to the Company shall be properly given if sent to or delivered
     to the Company at its registered office. Any notification, certificate or
     other notices sent by post shall be deemed delivered on the second day
     following the date of posting. All notices, documents or certificates given
     by or to an Option Holder (or his personal representative(s)) shall be sent
     at his risk.

8.2  Option Holders (or their personal representative(s)) may, at the Company's
     discretion, have made available to them copies of all notices and other
     documents sent by the Company to its holders of shares generally.

8.3  Subject to Rules 8.4 and 8.5, the Directors may at any time alter or add to
     all or any of the provisions of the Scheme.

8.4  No alteration or addition shall be made under Rule 8.3 which would abrogate
     or adversely affect the subsisting rights of an Option Holder unless it is
     made with the prior written consent of that Option Holder, such consent not
     to be unreasonably withheld or delayed.

<PAGE>

8.5  Subject to Rule 8.6, no alteration or addition to the advantage of Option
     Holders shall be made under Rule 8.3 without prior approval of the
     Remuneration Committee.

8.6  Rule 8.5 shall not apply to minor amendments to benefit the administration
     of the Scheme or to any alteration or addition which is necessary or
     desirable in order to obtain or maintain compliance with Schedule 5, to
     comply with or take account of the provisions of any proposed or existing
     legislation, law or other regulatory requirements, or to obtain or maintain
     favourable taxation, exchange control or regulatory treatment of the
     Company, any subsidiary of the Company or any Option Holder.

8.7  As soon as reasonably practicable after making any alteration or addition
     under Rule 8.3, the Directors shall give written notice thereof to any
     Option Holder affected thereby.

9.   GENERAL

9.1  In the event of any conflict between the rules of this Scheme and the terms
     of any Option Agreement, the terms of such Option Agreement shall prevail.

9.2  The Directors shall at all times ensure that there are sufficient Shares
     available as may be required to meet the subsisting rights of Option
     Holders by either ensuring that the Company shall at all times keep
     available for allotment unissued Shares at least sufficient to satisfy
     Options and/or procuring that sufficient Shares are available for transfer
     to satisfy Options.

9.3  The Company shall at its expense apply for the Listing of all Shares
     allotted pursuant to the exercise of any Option provided that Shares are at
     that time admitted to Listing.

9.4  The decision of the Directors in any dispute or question relating to any
     Option shall be final and conclusive.

10.  INLAND REVENUE REQUESTS

     The Company shall provide to the Inland Revenue (within such time limit as
     the Inland Revenue directs) any information required by it and Option
     Holders shall:-

10.1 promptly provide to the Company such information as it may reasonably
     request; and

10.2 consent to the Company providing such information concerning him to the
     Inland Revenue for the purpose of complying with such request from the
     Inland Revenue.

11.  TERMINATION

The Company in general meeting or the Directors may at any time resolve to
terminate this Scheme, in which event no further Options shall be granted, but
the provisions of this Scheme shall in relation to Options then subsisting
continue in full force and effect.

<PAGE>

12.  GOVERNING LAW

The Scheme and all Options granted under it and their interpretation are
governed by English law.

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