His departure had been rumoured since April, when he was demoted. His job was absorbed by David Berry, the US research director, and he became responsible for special projects.
The move is the latest in a series of management reshuffles and departures at Wellcome. Last month John Precious, finance director, quit abruptly 'to pursue other business interests', although he remains in place until the group finds a replacement.
The news was ill-received, particularly as the company is in the middle of changing its year end - its 10-month results are published next week.
John Robb is also under growing pressure to split his joint roles of chairman and chief executive - he took over the chairmanship last August after Sir Alastair Frame became unwell. He has since insisted he would be happy to give up the role if a suitable candidate could be found.
The management changes come at a difficult time for Wellcome, which has begun to face stiff competition for Zovirax, the herpes drug that supplies more than half its profits.
Wellcome's share price, which until recently languished at about 500p, rose 11p to 615p, as traders continued to argue that it was a likely bid target.
Speculation has centred on an American bidder in view of heavy trading in the US. However, Glaxo, the group that recently failed to buy PCS, the US pharmaceutical benefit manager, is another rumoured possibility.
Combining Wellcome and Glaxo would offer the possibility of stripping out a layer of research and development costs.Reuse content