Exhibit 4 --------- EMMET, MARVIN & MARTIN, LLP COUNSELLORS AT LAW 177 MADISON AVENUE 120 BROADWAY MORRISTOWN, NEW JERSEY 07960 (973) 538-5600 WRITER'S DIRECT DIAL NEW YORK, NEW YORK 10271 FAX: (973) 538-6448 _____ 1351 WASHINGTON BOULEVARD (212) 238-3000 2ND FLOOR _____ STAMFORD, CONNECTICUT 06902-4543 (203) 425-1400 FAX: (212) 238-3100 FAX: (203) 425-1410 http://www.emmetmarvin.com May 19, 2004 The Bank of New York as Depositary 101 Barclay Street New York, New York, 10286 Re: American Depositary Receipts for Common Shares, Par Value GBP 1 each, of GeneMedix Plc -------------------------------------------------------------------------- Ladies and Gentlemen: We refer to the registration statement to be filed on Form F-6 under the Securities Act of 1933 (the "Registration Statement") by the legal entity created by the agreement (the "Deposit Agreement") for issuance of American Depositary Shares ("ADSs") evidenced by American Depositary Receipts ("ADRs") for common shares, par value GBP 1 each, of GeneMedix Plc for which you propose to act as Depositary. We are of the opinion that the ADSs covered by the Registration Statement, when issued in accordance with the terms of the Deposit Agreement, will, when sold, be legally issued and will entitle the holders thereof to the rights specified in the Deposit Agreement and the ADRs. This opinion may be used by you as an exhibit to the Registration Statement. Very truly yours, /s/EMMET, MARVIN & MARTIN, LLP ------------------------------ EMMET, MARVIN & MARTIN, LLP