Mr Langley, who remains with the company while a specific project is completed, is to be replaced as head of Psion's finance function after 11 years at the computer group.
Having guided Psion through its 1988 flotation and seen the company grow from a pounds 4m business to one worth more than pounds 300m, he will be replaced by his number two, Marina Wyatt, a former Arthur Andersen accountant.
Psion has been one of the most dramatic stock market success stories in recent years, making share options awarded more than three years ago extremely valuable.
On the back of the company's successful Series 3A electronic organiser, the shares have soared from an equivalent of under 29p in August 1993 to yesterday's close of 451.5p.
Mr Langley exercised options over 330,669 shares at prices ranging from 24.7p to 59p for a total outlay of pounds 141,202. At yesterday's closing price those shares were worth pounds 1.49m and he immediately sold 181,000 to raise pounds 814,500. Following the disposal, Mr Langley retains a holding of 337,000 shares, worth pounds 1.52m.
Psion agreed to part company with Mr Langley last month in what one analyst described as a piece of "brutal realism". David Potter, chairman, described the parting as amicable but it was felt that Psion had outgrown Mr Langley's capabilities as finance director.