Sir Robin Day, the self-styled Grand Inquisitor, was the most celebrated TV interrogator of his generation, and possessed the skill to turn a political interview into a major political event.

His celebrated stewardship of the BBC Question Time programme for an entire decade made it the most popular current affairs programme of all time.

He was the scourge of statesmen and feared by all who submitted to his relentless questioning. His interviews were penetrating and persistent, but he was never discourteous nor did he ever resort to trickery to wheedle information out of his ''victims''.

Famed for his bow ties, Sir Robin established the criteria by which all TV interviewing came to be judged. Certainly in his heyday, and probably to this day, he has never been equalled by those who followed his profession.

His ability to pinpoint the key issue was one of the secrets of his success. His interviewees could always expect a hard time and occasionally there were angry exchanges, but he was invariably careful not to humiliate people.

At the height of his illustrious career, Sir Robin was more famous than most of the people he interviewed, although he was mindful never to be obtrusive in the exchanges.

He once had ambitions to become a Liberal MP, but had he entered Parliament, the world of broadcasting would have lost the pioneer and brilliant exponent of the art of the political interview.

In one of his books, Sir Robin laid down the ground rules for political interviewing:

l ''The interviewer should be firm and courteous. Questioning should be tenacious and persistent, but civil. I shudder to watch interviewers who think it clever to be snide, supercilious, or downright offensive.''

l ''The interviewer should be totally in charge. Too many TV interviews are incompetent because the interviewer is treated by the unseen producer as a puppet and is told what to ask.''

l ''The interviewer should know, or at any rate appear to know, at least as much about the subject under discussion as the person being interviewed.''

Robin Day was born on October 24, 1923, and educated at Bembridge School, and St Edmund Hall, Oxford. He served in the Army from 1943 to 1947.

Afterwards he studied law at Oxford and drifted to the Bar. But at the age of 30 he went to the United States where he worked in the British Information Services in Washington.

He returned to become one of the original newscasters at ITN and was parliamentary correspondent from 1956 to 1959. In that year, after failing in his attempt to become a Liberal MP, he joined BBC's Panorama programme, which he presented from 1967 to 1972, and was a contributor to for 30 years. He played a central role in eight general elections.

On BBC Radio 4, Sir Robin presented The World at One from 1979 to 1987. His radio work included Election Call, the morning phone-in which introduced a new form of election broadcasting, at a number of general elections.

Sir Robin was perhaps most noted for the Question Time programme which he chaired from 1979 to 1989 and which, under him, regularly attracted audiences of six to seven million.

Once he applied, without success, for the job of director-general of the BBC. He said afterwards: ''I did it for reckless amusement, not vanity. I have a built-in ability to anticipate non-success.''

There was often a kind of boisterous delight in the exchanges between Sir Robin and Margaret Thatcher when she came under his scrutiny. Once when he asked whether she intended to sack certain ministers, she replied: ''You are going further than I wish to go.''

Day: ''Well, naturally, that's part of my job, Prime Minister.''

Thatcher: ''Yes, indeed. It's part of my job to try to stop you.''

Once, Sir Robin even extracted a touch of vanity from Dennis Skinner, the left-wing Labour MP, who in more than 20 years in the Commons never achieved any front-bench office in his party.

Day: ''Have you ever been offered a job?'' Skinner: ''Oh no. No. Not in so many words. Naturally, a Prime Minister is not going to risk the rebuff.''

During his career, Sir Robin picked up many awards. These included the Guild of TV Producers and Directors Award, the Personality of the Year in 1957, the Richard Dimbleby Award for factual television in 1974, the Broadcasting Press Guild Award for Question Time in 1974, and the Royal Television Society Judges' Award for 30 years in TV journalism in 1985.

In retirement, Sir Robin continued to be impish, controversial and provocative whenever he thought the occasion demanded. In particular, he was critical about the way he thought the House of Commons, indeed Parliament itself, was being demeaned by the Tony Blair Government.

Sir Robin published his memoirs, Grand Inquisitor, in 1989. His previous books were, Television: A Personal Report, The Case for Televising Parliament and Day by Day. He was knighted in 1981.

And in 1999, he published a selection of his speeches, called Speaking for Myself, an amalgam which was described by Lord Jenkins of Hillhead as ''commemorative cocktails of warmth and raillery''.

His marriage to Katherine Ainslie in 1965 was dissolved in 1986. There are two sons.