It was the show that invented television satire, and paved the way for everything that followed. First screened in November 1962, That Was the Week That Was was irreverent and provocative, live television at its most exciting - and the first time political figures had been so publicly lampooned in more than a century, writes Penelope Dening

"They had been yearning for something like this for six years," says David Frost, front man of TW3, as it is more conveniently known. "Since Suez in 1956 and Look Back in Anger from John Osborne, also in 1956. They were fed up with the status quo - the young particularly. And the reaction of the audience proved that they were so much more intelligent than they were usually taken for. And the audience for the first week was, I think, two and a half million. Ten-thirty at night. And then it went four, five, seven, nine, 12 million."

But while his fellow performers are either dead (Bernard Levin, Roy Kinnear, Willie Rushton) or forgotten (Millicent Martin, Lance Percival), David Frost has became a global brand.

We meet in the London offices of his production company, David Paradine Ltd, a rare Frost-free zone in his empire. A Degree of Frost, The Frost Report, Frost over England, Frost over America - Who's Who lists more than 20 such programmes, the name conferring the broadcasting equivalent of the Good Housekeeping seal of approval: wholesome, reliable, but rarely revolutionary.

From royalty to presidents, he's the top people's interviewer of choice. Framed photographs of Frost with the famous crowd the walls of his outer office: a brief scan reveals Golda Meir, Tony Blair, the Clintons, Clint Eastwood, Angie Dickinson, Nelson Mandela. The roll-call of interviewees incudes the last seven US presidents and the last six British prime ministers, not to mention Bertie Ahern. So how does he do it?

Sitting opposite, on a chair too low for elegance, knees splayed out and shiny tie dangling, Frost is as keen and eager as a 14-year-old, not a hint of the film producer, impresario and media mogul who co-founded TV-AM and London Weekend Television. Frost's secret weapon, I decide, is his unexpected niceness and genuine interest in people. That he gets to choose his interviewees himself these days makes life easier, of course; as de facto executive producer on Breakfast with Frost - now in its 12th year - he and his editor have a mutual veto.

He is also the possessor of the most prodigious memory. Wherever our conversation roams, the names come tumbling out - from Millicent Martin's ex-husband to journalists remembered only by their mothers. Dates, venues, context are recalled without a blink, and not an autocue in sight.

This combination of informality and information was the biggest lesson he learnt from TW3, he explains. Keeping the tenor of the interview conversational and "never forgetting that you're talking to one, or two, or three people. Not to a crowd of three million". Unlike some of his high-profile colleagues, Frost sees no advantage in haranguing his interviewees, seeking to "open them up rather than close them down", while humour, he contends, can lighten even the most difficult encounter. His recent interview with Bill Clinton is a case in point.

Six weeks after the much-hyped memoirs had been published, all the obvious questions about Monica Lewinsky that had already been asked "30 or 40 times" before. A different approach was needed.

"So I said: 'I hope you won't be disappointed, but I'm only going to ask you two questions about Monica Lewinsky.' "

The wry chuckle that came in response to this sally was enough to disarm the former president for a moment. The first question, concerning Lewinsky's assertion that the relationship had ruined her life, resulted in a calm appraisal of her virtues - an unexpected take, Frost says.

"The simple follow-up 'did you love her?' brought the answer: 'No. And I think that was true on both sides.' Both questions he had never been asked before."

Since 1963, when TW3 was exported successfully to the US, David Frost's career has straddled the Atlantic, and there have been phases when he took the red-eye between London and New York twice a week. In 1977, his interview with Richard Nixon, three years after Watergate, pulled in 45 million viewers in the US alone, the largest audience ever for a news programme.

"Nixon was unique in the sense that, although he was a professional politician, he had no small talk," Frost says. "So he would be awkward in conversation off camera, but once you got him on camera, and you asked questions that absorbed him, he spoke more freely. In the end he made more of a mea culpa than we had hoped, thought possible, or anticipated. And that was very exciting."

Being known in the US, he contends, also helps persuade Americans to appear on his British show, simply because "they know who you are". He got the first full-length interview with George W. Bush last November, he says, though his existing convivial relationship with Bush senior doubtless did no harm. Frost and Bush senior had first met for The Next President with David Frost series, involving all the prospective candidates in 1988, and it was an interview which turned out, Frost says, to be the most unexpected of his career.

"I was warned that he was a difficult interview," Frost recalls. "And the reverse was the case. Somehow we hit it off from the word go. He was moving, forthcoming, answered everything. I remember a story about his daughter Robyn, who he'd lost to leukaemia at the age of four. He was very moving about that, very moved as well. And it was just a magic hour, an absolute revelation. The result was we went on to do lots more.

"I did an interview - which was a secret at the time - nine days after the Gulf War. I gave the tape to him and we only released it five years later."

The suggestion had come from Frost himself.

"It was the day after we won that war," he says. "I was in Monte Carlo, so I rang him at 7.25 a.m. Washington time and I said: 'You really ought to do an interview that captures your feelings now - preferably with me, but with somebody. You should do it because you won't be able to recollect, when you write your memoirs in three years' time, the way you're feeling now.' We did it the next week at Camp David. It was a fantastic experience because there was the president, Barbara, \ Brent Scowcroft, the national security adviser, and Marlin Fitzwater [White House press secretary] - the four of them with their diaries. It was fantastic."

Are there times, I ask, when he has to pinch himself that he is not only recording history but part of it?

"Absolutely," he says. "I feel like that a lot of the time. Here you are, talking to someone and being paid for it, when you'd count it a privilege to talk to them anyway."

Breakfast with Frost has been running now for 12 years. Its timing - Sunday morning - ensures that it sets the political agenda for the following week, making TV and radio news that lunchtime and the newspapers on Monday morning. As well as politicians - national and international, chosen on a largely stop-press basis - the weekly guest list is leavened by actors, musicians and sports personalities, jazz being his editor's particular interest and football his own. David Seaman, the former England and Arsenal goalkeeper, is a personal friend; godfather, indeed, to the Frosts' youngest child.

Enduring personal friendships are one of the many pluses of the interviewing chair, he says. Once he even fell in love on air, he admits, in 1970 with the actor/singer, Diahann Carroll. The feeling was mutual and the airwaves are said to have crackled with the sudden surge of electrical activity. The relationship lasted "three wonderful years".

The man whom comedian Frankie Howerd famously described as wearing his hair back to front is now a fixed star in the broadcasting firmament. In the intervening 40years the trademark mini-quiff has become a halo of greying fluff. But would the angry young Turk of 1962 see Sir David (he was knighted in 1993), the fellow who cosies up to the great and the good, as a suitable candidate for the edge of his tongue? Has he, in short, sold out to the establishment that was once the enemy? He takes a long puff on his cigar.

"Well, I have sometimes said that I don't think I have joined the establishment, but that the establishment has joined me," he says. "But in general I think that the establishment no longer exists, that it's largely a thing now of placements at a hunt ball, a social thing rather than a political thing."

One recent experience, however, caused him to doubt this view.

"When I did the film about Nick Leeson [Rogue Trader, the story of the Barings Bank scandal in Hong Kong] I did come to believe that if he'd been born Nicholas Fotheringham Leeson, he would have got four years in the Ernest Saunders Memorial Suite in Ford Open Prison rather than being allowed to go to Singapore Changi Jail," he says. "And I did feel that there was an establishment working there and that it also served as a cover-up. If the case had been heard in the UK, there would have been a lot more focus on Barings and their negligence and greed, and the degree to which they were protecting their bonuses, compared to what Nick Leeson had done."

As for whether the young David Frost would see his current incarnation as a potential target for satire, the answer is: "Possibly. But I hope too that he would approve of what I had done."

At 65, David Frost shows no sign of slowing down. He isn't a workaholic, he says, though he might admit to being a telephone-aholic, "but I don't like to waste money and, even more, I don't like to waste time". As for giving it all up, he looks bemused. "I can't imagine what it would be like to retire, and I don't plan to find out," he says.

David Frost appears in the first of a new series of Eagle Star Face to Face Interviews by Gay Byrne at the National Concert Hall, Dublin next Monday. The series continues with former world heavyweight boxing champion George Foreman on November 8th and astronaut and rocket scientist Buzz Aldrin on November 18th. Booking: 01-4170000 or www.nch.ie

Name: David Paradine Frost

Born: 1939

Educated: Cambridge University

Family: In 1983 he married Lady Carina Fitzalan-Howard, second daughter of the Duke of Norfolk; they have three sons

Claim to fame: Has interviewed seven American presidents and six English prime ministers

Most confrontational interview: Enoch Powell

Worst live TV moment: Members of Jerry Rubin's Yippie (Youth International Party) movement taking over the studio during The David Frost Show in 1970, firing a water pistol at Frost and forcing him to continue the programme from another studio

Most surprising interview: George Bush senior

Longest interview: Richard Nixon (24 hours)

Key prop: The "instantly recognisable" yellow sofa on the Breakfast with Frost set