EXHIBIT 19 [LETTERHEAD OF CAMBRIDGE ANTIBODY TECHNOLOGY] Dr David Ebsworth Danziger Strasse 17 51491 Overath Germany 22 January 2003 Dear Dr Ebsworth Service Agreement with Oxford Glycosciences plc We are writing to you in relation to the proposed merger of Oxford Glycosciences plc with Cambridge Antibody Technology Group plc ("the Merger"), which is proposed to be effected by a scheme of arrangement pursuant to section 425 of the Companies Act 1985. Subject to the Merger becoming effective by 30 April 2003: (a) we would propose that Clause 20.1 of your service agreement with Oxford Glycosciences plc dated 22 May 2002 ("the Service Agreement") be varied by increasing the period within which you are required to give notice of termination of your employment following the Merger in accordance with that clause from 30 days to 12 months following the date upon which the Merger becomes effective; (b) in consideration of this, you agree (without prejudice to your continuing employment with Oxford Glycosciences plc) at our request made at any time to resign promptly from the board of Oxford Glycosciences plc and from the board of any member of the Oxford Glycosciences group of companies without any claim against Oxford Glycosciences plc or any of the members of the Oxford Glycosciences group of companies, whether in relation to your employment with or office as a director of such companies, arising from such resignations. Should you fail to do so, the board of Cambridge Antibody Technology Group plc shall be irrevocably authorised to appoint some person in your name and on your behalf to sign any documents and take such other steps as are necessary to give effect to such resignations. For the avoidance of doubt, the above variation would apply only to the Merger and not to any other change of control that may take place after the Merger has been implemented. We should be grateful if you would confirm your agreement to the proposed variation by executing this letter below. This letter may be executed in counterparts and by the parties to it on separate counterparts, each of which when so executed and delivered shall be an original, but both counterparts shall together constitute one and the same instrument. EXECUTION: Dated 22 January 2003 SIGNED AND DELIVERED as a DEED by ) /s/ JOHN ASTON JOHN ASTON, Director and DIANE MELLETT, ) Secretary duly authorised for and on behalf of ) /s/ DIANE MELLETT CAMBRIDGE ANTIBODY TECHNOLOGY GROUP PLC ) SIGNED AND DELIVERED as a DEED by DAVID ) /s/ DAVID EBSWORTH EBSWORTH in the presence of ) Witness' signature /s/ Graham Gibb ------------------------------- Witness' name (in capitals) GRAHAM GIBB ------------------------------- Witness' Address ONE BUNHILL ROW LONDON EC1Y 8YY ------------------------------- Occupation: SOLICITOR -------------------------------