'Call me David Flunkett'

If you can't stand the heat, get out of the kitchen,' an aide to U.S. President Harry S. Truman once said, referring to the pressures of holding political office.

During the course of my political career, I have become pretty used to such pressures, especially in recent years as Home Secretary. But nothing in politics ever prepared me for the torture of participating in the celebrity Christmas edition of Mastermind, that most enduring of all TV quizzes, once hosted by Magnus Magnusson and now presented by John Humphrys.

Fear, anxiety and a sense of impending humiliation were my primary emotions as I took part. Answering questions in the noisy bear-pit of the House of Commons is a doddle compared to the mental agony of the Mastermind ordeal.

I would rather spend a day in front of the Home Affairs Select Committee than another terrifying minute on Mastermind. As a guest on Radio Four's Today programme, I have of course been grilled many times by the famously aggressive John Humphrys. But I found him a much more intimidating figure as the host of Mastermind than he is behind the microphone in the Today studio.

At least on the radio, I can engage in debate with him and occasionally even some banter. But on Celebrity Mastermind, all such human interaction disappeared. He appeared as a ruthless automaton, firing out ever more esoteric questions which demanded an instant, factual answer. There was no room for argument or challenge.

The cold impassivity of the presenter is one of the strategies adopted on Mastermind to heighten its tension. Others include the solemn, doom-laden music, and, above all, the notorious black leather chair used for each interrogation.

I have to admit that, when it was my turn, I was so nervous, I began to feel as if the chair had almost become an electric one. It is quite simply terrifying.

THIS should come as no surprise. After all, the idea for the programme itself arose out of interrogation in World War II. Yes, seriously. It is based on the experiences of the original creator Bill Wright when he was a prisoner of war. Being forced to give his 'name', 'rank' and ' number' made such a lasting impression on him that he decided to adapt it to 'name', 'occupation' and ' specialised subject' for this latter-day form of inquisition. It is the nature of the questioning, and not the questions themselves, that pose the problem.

So why, given the menacing nature of the programme, did I ever agree to take part? Well, for a start, I have long been a fan of Mastermind, so I was intrigued to know what it would be like to be a participant rather than merely a listener. I thought, perhaps naively, that it might actually be fun.

Furthermore, I have always enjoyed pub quizzes, believing that I have a pretty good general knowledge - although I have

to say that I never get time to actually participate. And there was also the carrot that, through my appearance, I would be raising funds for an excellent charity, a local children's hospice.

I suppose I had foolishly thought that since this was a celebrity Christmas edition, the programme might be more relaxed than usual. I had even anticipated that I might be able to make a few jokes with John Humphrys.

For instance, if stumped by a particularly awkward question, I would ask him if I could 'phone a friend' or 'ask the audience'. No such luck! This was deadly serious, and not a whiff of festive spirit diluted Humphrys's stern manner. He almost seemed to relish the chance to see a politician floundering for an answer.

Inevitably, I agonised about my choice of specialist subject. Superficially, the obvious choice for me would, of course, have been 'politics'.

Indeed, the other three celebrity contestants - Shaun Williamson, the EastEnders actor; Antony Worrall-Thompson, the chef; and Jeremy Bowen, the BBC's renowned foreign correspondent - all chose subjects related to their professional fields.

For example, Bowen chose the 1967 Six Day War in the Middle East, about which he has just written an acclaimed book. But because politics is such a sensitive area, affecting so many lives and the running of the country, I felt it best to steer clear of the subject.

A wrong answer from a serving Cabinet minister on a controversial issue could become a news story in itself, something I was obviously keen to avoid. So instead, I plumped for the Harry Potter books.

I had loved the first four, and was enjoying the fifth when the BBC approached me about Mastermind. Besides, I thought Harry Potter would be far more entertaining for viewers than another dreary dose of politics, which already fills the news for most of the year.

In particular, a subject like Harry Potter, I believed, would engage

children at home. Being Home Secretary and dealing with issues like asylum and international terrorism doesn't exactly leave me much time for other things.

But nonetheless everyone pitched in, with my driver, private office and friends using odd moments to help me swot up.

I was surprised by how much my mind went blank, with great chunks suddenly disappearing from my memory. On Harry Potter, I was asked to name the emblem of Hufflepuff (one of the four houses at Hogwarts, Harry's school).

Of course, I know the answer - a badger - and would have shouted out if I had been sitting at home with friends. But in the Mastermind chair, I somehow could not understand what Humphrys was driving at.

Another question in the general knowledge section related to the Irish city of Waterford, where the renowned crystal is made. Normally, I would have had no problem with this because I passed through the city during my honeymoon there with my first wife, Ruth. But, in the black chair, I heard myself say 'Pass'.

Equally embarrassing was my failure to identify the British middle distance runner who won Olympic gold in 1980 and 1984. Of course, it was Sebastian Coe.

AGAIN, this was an answer I should have known because Coe was brought up in Sheffield and I had given him a civic reception when I was leader of Sheffield City Council in the 1980s.

I've been asking myself how I could forget so much. After all, so much of my political work requires an ability to absorb huge amounts of material and present them in public. Moreover, because of my blindness, I have learned to focus hard on memorising information.

For example, in the wake of September 11, I did the equivalent of a Phd in international terrorism over a period of just three months. I have found that my mind, in one respect, resembles a kind of computer chip, which can be temporarily be filled with data to accomplish a certain task.

Perhaps once the objective is achieved, the chip is wiped clean to create memory space for the next job. I've always pointed out when asked about my memory that I'd be no better than the next man or woman at remembering a Shakespeare sonnet; I was reminded of this when doing Mastermind!

Yet such a memory-wiping facility is the last thing you need when you're in the Mastermind chair. Well, that's my excuse anyway!

But, for all the trauma, it was still an enriching experience. I've developed an even deeper appreciation of Harry Potter and raised £2,500 for the Bluebell Wood Children's Hospice.

What's more, I'll never have the slightest worry about facing John Humphrys again on the Today programme.

And the next time I'm asked a difficult question, either in Cabinet or the Commons, I'll know exactly what to say - 'Pass'!

CELEBRITY Mastermind is on BBC2 on Boxing Day at 8.25pm. To donate to Bluebell Wood Children's Hospice, call 01302