LONDON - British Biotech plc has signaled more changes at the top with the disclosure that John Raisman is to retire as nonexecutive chairman Sept. 30, just one week after CEO Keith McCullagh is due to leave the company.

Raisman will be replaced by Christopher Hampson, who was a main board director of the chemical company ICI plc until his retirement after 38 years with the company in April 1994. Hampson was subsequently chairman of Yorkshire Electricity Group plc, an electricity supply company. He is currently nonexecutive chairman of a building materials company, RMC Group plc, and holds a number of other nonexecutive directorships.

Though he will not take up the chairmanship until October, Hampson formally joined the board of British Biotech, of Oxford, U.K., Aug. 4. His first task is to find a CEO to replace McCullagh, who has been forced to leave the post over allegations of misleading shareholders by inflating the prospects for drugs in development, of inappropriate commercialization plans and of improper share dealings.

The allegations were made by Andy Millar, former head of clinical development, who was fired by the company in April.

News of Raisman's retirement did not halt the slide in British Biotech's share price, which fell by 8 percent last week to close Friday at £0.315. This is 10 percent of the share price's highest value, in 1996, and, given that the company had £132.8 million cash at the end of April 1998, very close to the cash pile equivalent of £0.30 per share. - Nuala Moran