Roger Needham, who has died aged 68, helped keep Cambridge University at the forefront of computer research for more than 20 years, and set up Microsoft's first overseas research organisation alongside his beloved computer lab. Microsoft was US-based, and could have sited its new research lab anywhere in Europe.
However, given the company's somewhat patchy reputation, it needed someone whose work was respected and whose integrity was beyond question, in order to attract the best researchers and keep them happy. Needham fitted the bill perfectly, and Microsoft let him get on with it.
He revelled in his new-found freedom. He said: "One of the things I've noticed, having moved from being an academic to doing this job, is that I'm trusted now, and I wasn't then."
Needham was neither a computer geek nor an absent-minded professor. He was a quietly spoken but convivial, down-to-earth type. One PhD student, Sape Mullender, now at Bell Labs, recalled feeling "somewhat apprehensive to meet one of the grand old men of computer science. He turned out not to be intimidating at all and immediately invited me into that hallowed place where he carried out much of his best research - the pub."
Adjourning to the pub allowed for the serendipity that Needham prized highly, and he was very fond of a definition that he credited to a former colleague, Sir Hans Kornberg: "Serendipity is looking for a needle in a haystack and finding the farmer's daughter."
The combination of affability, practicality, a deep sense of public service and a sharp, logical mind made Needham a natural committee man, and he spent rather a lot of his life sitting on them. These ranged from the Alvey committee, intended to stimulate Britain's hi-tech research, to the Defence Scientific Advisory Council, to the (in his words) "sometimes-lamented" University Grants Committee. He was also a trustee of the left-leaning Foundation for Information Policy Research and a Labour party district councillor.
Needham grew up in Sheffield and Doncaster, where his father worked in the coal industry. He won a scholarship to Cambridge and gained his BA in mathematics and moral science in 1956. In his final year, he became interested in the Cambridge Language Research Unit. In a brief memoir published on the web, his wife Karen Sparck-Jones, professor of computers and information in the university's computer lab, says it was "originally a lively discussion group interested in language and translation, subsequently funded to do research on automatic translation". This sparked Needham's interest in computing. He did a diploma in numerical analysis and automatic computing in 1957, and worked at the unit until 1962, while researching his PhD.
During this time, Needham married Karen, then a fellow PhD student. They built a house and in 1961 they also bought their first boat; they later sailed round the east coast in an 1872-vintage Itchen Ferry Cutter. Both projects became life-long loves.
After graduating, Needham joined Cambridge University's mathematical (later, computing) laboratory, run by the renowned computer scientist Maurice Wilkes. He succeeded Wilkes as head of the laboratory in 1980, and served as professor of computer systems until 1998.
During his 40 years at the lab, Needham saw computing develop from Wilkes's EDSAC (Electronic Delay Storage Automatic Calculator) - the basis of LEO or Lyons Electronic Office, the first commercial computer - to today's cheap, ubiquitous systems. But he rejected the idea that he had lived through the information technology revolution. "I believe, on the contrary, that it has not happened yet, and that it is only beginning," he said.
None the less, he was involved with the development of some groundbreaking systems and many original ideas. This included work on a one-way function to protect passwords, which became a common feature, the design and construction of the Cambridge Ring (one of the first high-speed local area networks) and the Cambridge Model Distributed System, which researched network-based computing. Most of these were team projects, but Needham was a team player.
Needham was one of the first to appreciate the need for computer security, and in 1967, he devised a method for encrypting password files in a secure way. In 1978, he and Michael Schroeder published research on a system for identifying users by exchanging data, usually in passwords. The Needham-Schroeder protocol for authentication had a flaw, but they produced an enhanced version later.
Needham retired from the university after becoming managing director of Microsoft Research Limited, Cambridge, but becoming "Bill's don" only made him more prominent. The research lab that started with three people in rented accommodation ended up with 55 researchers in a huge building (renamed in Needham's honour) with room for many more. It is an impressive testament both to the quality of the research at the university and the regard in which Needham was held.
Late last year, Needham was diagnosed with incurable cancer. Microsoft Research organised a technical symposium, Roger Needham: 50 and 5, to celebrate his 50 years in Cambridge and five with Microsoft. The speakers included Maurice Wilkes and Rick Rashid, head of Microsoft Research in Seattle.
Needham, by now in a wheelchair, donned a workman's helmet, saying he was still very much a practical engineer. He always said that "if there wasn't an industry concerned with making and using computers, the subject wouldn't exist. It's not like physics - physics was made by God, but computer science was made by man. It's there because the industry's there."
His wife survives him.
· Roger Michael Needham, engineer and computer scientist, born February 9 1935; died March 1 2003