Mr Noble was a key figure in the group's relations with the City and the press and one shareholder suggested yesterday he had been guilty of "over-egging" the story at times. In the six months between November 1995 and May 1996, the share price tripled, putting Biotech within sight of entering the FT-SE 100 index, since when it has fallen close to 100p. But Keith McCullagh, chief executive, said there had been no dissatisfaction with Mr Noble. "James's management of the accounts has been exemplary."
The company was moving to a new stage of its development as it established trading subsidiaries on the Continent, which would require the establishment of systems and procedures to match, Mr McCullage said. "James has been thinking whether he wants that as the next stage of his career and he has come to the conclusion that he doesn't."
Mr Noble, who arrived from Kleinwort Benson in 1990, is understood to be looking at several other options, including joining some "young growing companies".
Mr Noble, who was paid pounds 189,000 last year, made pounds 1.68m from option sales in December 1995 and will retain options over a further 1.07 million shares, showing a profit of pounds 2.19m at current prices. However, he relinquishes 1.4 million options which could net him a potential profit of pounds 2.85m but which cannot yet be exercised. Mr McCullagh said any pay-off for Mr Noble's 12 month contract would depend on the speed at which he moved to a new job.
Despite the company's reassurances, many in the City remained sceptical about Mr Noble's departure. A group institutional shareholder said: "It seems a bit odd that somebody would leave a company like British Biotech when it is just going to crank up."