EXHIBIT 10


                       DIRECTOR'S IRREVOCABLE UNDERTAKING

To:      The Directors
         Cambridge Antibody Technology Group Plc
         Milstein Building
         Granta Park
         Cambridgeshire CB1 6GH
and

         Merrill Lynch International ("Merrill Lynch")
         Merrill Lynch Financial Centre
         2 King Edward Street
         London EC1A 1HQ
                                                         Date 22nd January, 2003

Dear Sirs

Offer for Oxford GlycoSciences Plc (the "Target")

I understand that Cambridge Antibody Technology Group Plc (the "Bidder") is
considering merging with the Target, which merger will be effected by way of a
scheme of arrangement (pursuant to section 425 of the Companies Act 1985) (the
"Scheme") substantially on the terms and conditions set out in the attached
draft press announcement (the "Press Announcement"), together with such
additional terms and conditions as may be required to comply with the City Code
on Takeovers and Mergers (the "Code") and any other applicable law or regulation
and any additional terms and conditions agreed between Bidder and Target (the
"Merger").

1.    Warranties and undertakings

      I irrevocably confirm, undertake and warrant to the Bidder and Merrill
      Lynch that:

      (a)   I am the registered holder and/or beneficial owner of the issued
            fully paid shares of 5p each of the Target ("Target Shares"),
            details of which are set out in Part A of the Schedule hereto
            ("Existing Shares");

      (b)   I will not, prior to the Effective Date (as defined in the Press
            Announcement) or the date upon which this undertaking shall lapse in
            accordance with paragraph 6 below, whichever occurs earlier:

            (i)   accept any offer in respect of or sell, transfer, encumber,
                  charge, grant any option over or otherwise dispose of or
                  permit the sale, transfer, charging or other disposition or
                  creation or grant of any other encumbrance or option of or
                  over any of the Existing Shares or any other shares or
                  securities of the Target issued or


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                  unconditionally allotted to me or in which I may otherwise be
                  interested after the date of this undertaking ("Further
                  Shares");

            (ii)  enter into any agreement or arrangement or incur or allow to
                  arise any obligation (conditional or unconditional) to do any
                  of the acts referred to in paragraph 1(b)(i) of this
                  undertaking;

            (iii) dispose of any other shares or securities of the Target or any
                  interest therein (including any derivatives referenced to any
                  such securities).

      (c)   the Schedule hereto sets out full and accurate details of all the
            shares and other securities in the Target in which I have or am
            entitled to acquire an interest; and

      (d)   I have the full power and authority (free from any legal or other
            restrictions) (and will at all times continue to have all relevant
            authority) to enter into and perform this undertaking in accordance
            with its terms.

2.    Undertaking to vote in favour

      I irrevocably undertake that:

      (a)   I shall or, where applicable, will procure that the registered
            holder of the Existing Shares and the Further Shares (if applicable)
            will, in person or by proxy cast all votes (whether on a show of
            hands or a poll) in relation to the Existing Shares and the Further
            Shares at the Oxygen Court Meeting (as defined in the Press
            Announcement) and the Oxygen EGM (as defined in the Press
            Announcement) in favour of the resolutions to approve the Scheme,
            the reduction of the Target's share capital and the amendment of the
            Target's articles of association together with any other resolutions
            set out in the Scheme Document (as defined below) (the
            "Resolutions") and against any resolution or proposal to adjourn the
            Oxygen Court Meeting (as defined in the Press Announcement) or the
            Oxygen EGM (as defined in the Press Announcement); and

      (b)   I shall after the despatch of the circular to be sent to
            shareholders of the Target containing an explanatory statement in
            respect of the Scheme (the "Scheme Document") (and without prejudice
            to my right to attend and vote in person at the Oxygen Court Meeting
            and the Oxygen EGM), return the signed forms of proxy enclosed with
            the Scheme Document (completed and signed and voting in favour of
            the Resolutions) in accordance with the instructions printed on
            these forms of proxy, so that they are received by no later than
            3.00 p.m. on the 15th day after the despatch of the Scheme Document.


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3.    Documentation

      (a)   I consent to the issue of the Press Announcement incorporating
            references to me and to this undertaking, subject to any amendments
            which may be agreed by me or on my behalf by a member of the board
            of directors of the Target.

      (b)   I understand and agree that, in accordance with the Code,
            particulars of this undertaking and discloseable holdings of, and
            dealings in, relevant securities of the Target will be contained in
            the Scheme Document and that particulars of this undertaking will
            also be contained in the document comprising listing particulars or
            supplementary listing particulars to be issued by the Bidder (the
            "Listing Particulars") and the circular to the Bidder's shareholders
            to be issued by the Bidder (the "Circular") and that copies of this
            undertaking will be available for inspection until the Effective
            Date (as defined in the Press Announcement).

      (c)   I undertake to provide you with all such further information in
            relation to my interests and those of any person connected with me
            as you may require in order to comply with the requirements of the
            London Stock Exchange, the UK Listing Authority, the Panel on
            Takeovers and Mergers and any other legal or regulatory requirements
            for inclusion in the Scheme Document, the Listing Particulars, the
            Circular (or any other document required in connection with the
            Scheme or the Merger), having verified that all such information is
            true and accurate and not misleading and that there are no omissions
            therefrom.

4.    Director's undertakings

      I, being a director of the Target, irrevocably undertake that I will, on
      the Scheme becoming effective, exercise my powers as a director of the
      Target to appoint promptly any persons nominated by the Bidder to the
      board of the Target and shall approve alternate directors nominated by
      such newly appointed directors.

5.    Specific Performance

      I recognise and acknowledge that if I should fail to perform my
      obligations set out in this undertaking, or should otherwise be in breach
      of any of those obligations, damages may not be an adequate remedy and
      that, in addition to all other remedies the Bidder may be entitled to as a
      matter of law, the Bidder may (at the Court's discretion) be entitled as a
      matter of law to the remedies of injunction, specific performance and
      other equitable relief and that no proof of special damages shall be
      necessary for the enforcement of this undertaking.

6.    Lapse

      All obligations in this undertaking will forthwith lapse:


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      (a)   if the Press Announcement is not released on or before 28 February
            2003; or

      (b)   if the Scheme Document, Listing Particulars and Circular are not
            issued to shareholders by no later than the date falling 28 days
            after the Press Announcement is made; or

      (c)   if the Effective Date (as defined in the Press Announcement) has not
            occurred by 30 April 2003.

      Any lapse of obligations pursuant to the terms of this paragraph 6 shall
      have no effect on the rights and liabilities of the parties which have
      accrued on or prior to such lapse.

7.    Confirmations

      I confirm that:

      (a)   in executing this document I am not a customer of Merrill Lynch for
            the purposes of the rules of the Financial Services Authority and
            that accordingly Merrill Lynch does not owe me any of the duties
            which it owes to its customers; and

      (b)   I have been given an adequate opportunity to consider whether or not
            to give this undertaking and to obtain independent advice.

8.    Interpretation and general

      (a)   In this undertaking:

            (i)   the expression the "Scheme" shall (where appropriate) extend
                  to any increased or revised proposal by the Bidder in respect
                  of the terms of the Merger or any offer by the Bidder to
                  acquire all or any of the issued ordinary shares of the Target
                  which represents, on such basis as Merrill Lynch may
                  reasonably consider appropriate, no diminution in the value of
                  the consideration offered under the terms set out in the Press
                  Announcement;

            (ii)  references to the "Scheme Document", the "Listing Particulars"
                  and the "Circular" shall (where appropriate) include and
                  extend to any revised scheme document or supplementary listing
                  particulars;

            (iii) references to "Existing Shares" and "Further Shares" shall
                  include and extend to any other shares or securities of the
                  Target attributable to or derived from the Existing Shares or
                  Further Shares and any securities issued in respect of the
                  Existing Shares or Further Shares or into which the Existing
                  Shares or Further


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                  Shares may be converted as a result of any reorganisation of
                  the share capital of the Target.

      (b)   Any time, date or period mentioned in this undertaking may be
            extended by mutual agreement between the parties hereto or otherwise
            as provided herein but as regards any time, date or period
            originally fixed or so extended as aforesaid time shall be of the
            essence.

      (c)   With regard to any of the Existing Shares or Further Shares not
            registered in my name, the confirmations, warranties and
            undertakings contained in this undertaking are given by me on behalf
            of those persons in whose names such of the Existing Shares or
            Further Shares are registered and I undertake to ensure the
            compliance by such persons with those confirmations, warranties and
            undertakings.

      (d)   No term of this undertaking is enforceable under the Contracts
            (Rights of Third Parties) Act 1999 by a person who is not a party to
            this undertaking other than the Bidder and/or Merrill Lynch.

9.    Governing law

      (a)   This undertaking shall be governed by and interpreted in accordance
            with English law.

      (b)   I hereby submit to the exclusive jurisdiction of the High Court of
            Justice in England.

I have shown my acceptance of the terms of this undertaking by executing it as a
deed at the end of the Schedule.


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                                    Schedule

                                  Rajesh Parekh

Part A - Registered and beneficial holdings of Oxygen Shares

Number of shares: 71,212

Part B  - Options and Oxygen Shares



         (1) Scheme               (2) Date of Grant      (3) Exercise Price ((pound))     (4) Number of Shares
                                                                                          
         1994 Scheme              Prior to 31/12/01                  1.25                           8,000

                                  Prior to 31/12/01                  1.25                          80,000

                                  Prior to 31/12/01                 1.425                          40,000

                                  Prior to 31/12/01                 2.125                          80,000

      Executive Scheme            Prior to 31/12/01                 17.25                          51,000

                                  Prior to 31/12/01                15.325                          30,000

                                  Prior to 31/12/01                 11.00                          20,000

                                  Prior to 31/12/01                 11.00                          20,000



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EXECUTION:

Dated:                              22nd January, 2003

SIGNED AND DELIVERED AS A DEED             )

by       RAJESH BHIKHU PAREKH              )

acting by his duly appointed attorney      )

DAVID RAYMOND EBSWORTH
........................................     )

in the presence of:                         )


Signature of Witness:  Graham Gibb

Name of Witness:       GRAHAM GIBB

Address:               ONE BUNHILL ROW, LONDON EC1Y 8YY

Occupation:            SOLICITOR


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