I consoled Steve by telling him that he'd stumbled across a golden rule that Tom and I had invented nearly 30 years ago. We would only ever meet accidentally. There would be no assignations, no letters, no phone calls. It was, I explained, all part of being an urban bohemian. I mean, Jack Kerouac didn't ring up William Burroughs to arrange a suitable date for a visit, did he? He simply took to the road and turned up at Burroughs' place when the spirit moved him.

If Steve had been able to spare the time I'd have gone on to explain that such an arrangement worked remarkably well back in the late 70s when neither Tom nor I seemed to have a home to go to and were around Soho most nights of the week. In that era it was a fair bet that if Tom wasn't chatting to Francis Bacon in the French House, he'd be tucked up with Jeffrey Bernard in the Coach and Horses. But when neither of us could maintain that sort of pace we almost completely lost touch. We were really only drinking partners and when the drinking stopped there was nothing else to be said or done. Tom simply doesn't function in people's houses or over dinner tables. He is only truly himself, in full Technicolor wide-screen glory, when he is standing by a bar and bashing the optics. "Two more gins in there, landlord," he roars, passing over his still half-full glass. "And another treble vodka for you, Laurie?" "No, no. It's my shout, Tom." "Don't be silly, I've just heard myself earning a hundred pounds." He was often literally correct. Even as he spoke I could hear his reverberating baritone endorsing yet another product on the saloon bar telly.

I suppose it was a combination of these memories and Steve's anguished nudging that made me decide to break the golden rule. At least I had a sort of excuse. I rang Tom and said I'd like to meet up and interview him for the New Humanist.

From the beginning I knew there was little chance of such an interview getting any great subjective purchase upon the real Tom Baker. This isn't because he lacks an interest in the inner life - he's a compulsive reader of such geographers of human consciousness as Philip Roth and Saul Bellow - but because conversation for him is always in the nature of a performance. He has no time for stuttering confessions or intimate revelations. Instead, like so many other Liverpudlians, he likes nothing more than telling a good tale.

So, when we finally settle down in an Indian restaurant round the corner from The George, and I prompt Tom to talk about his childhood, I know I'm in for some well-rehearsed runs. "Were you a very Catholic boy?"

"Oh yes. I was intensely Catholic. Intensely. Of course, in retrospect I just adore the wonderful cunning of Catholicism. The wonderful paradoxical cunning of persuading the poor that they had actually been chosen by God, that it was actually a stroke of luck that they were fucking poor. I remember my old dad saying: 'Thank God, mother, that we are not rich.' Remember that line in the Beatitudes: 'Blessed are the meek, because they shall inherit the earth.' I think it was Mark Twain who said that if the meek do inherit the earth it will be very interesting to see how long they hold on to it. All those religious ways of comforting people with no other hope in life. I imagine that young Muslims going into battle are equally reassured by the thought of dying and getting together with seventy-two lubricious young virgins who never grow old. Seventy-two. Think about it. I mean that is an awful lot of tits. And if you are a poor misunderstood Muslim who nobody likes or wants then that must be an awfully tempting prospect."

I can see our waiter hovering. Tom waves his hand across a couple of items on the menu and keeps talking. "Of course, you have to remember that I came very late to sin. I didn't know about it until I was eight years old. So when I had to go to confession before that age I never had anything to say. But the other boys used to tell me to say that I'd had an impure thought. Nowadays whenever I have an impure thought I can hear the priest wheezing. Because all priests smoked and they all smoked Capstan Full Strength. Full Strength. They all had emphysema. They used to say, 'Now, this impure thought' - wheeze wheeze - 'did you take any pleasure in it? And how many times' - wheeze wheeze - 'did you have that thought?' And then he'd say - wheeze wheeze - 'did pollution take place'. Pollution! What an appalling word!"

By this stage I'm already tempted by the idea of simply letting Tom roll on. There'd be lots of laughs along the way. But this is supposed to be a relatively serious business - it's for New Humanist for God's sake - so I spike his guns by pointing out to him that his rollicking scabrous stories of youthful Catholicism are a little difficult to reconcile with the hard historical fact that he decided at the age of 15 to go into a monastery and ended up staying there for five long years. Why did he go there in the first place?

He's ready for this one as well. "I went because there wasn't much room for me at home. The house was a bit crowded. No, seriously." For a second he considers another trope and then relents. "Well, I think I'd never really recovered from failing the 11 plus. It was a terrible blow to me. For boys in Liverpool the only way out was through an education. Ordinary boys went to work on the docks or became waiters at the Adelphi or joined the Merchant Navy. So, the only alternative for me was to do something heroic. Make a grand gesture, like joining the Foreign Legion or the SAS. Joining a religious order was like that. Not only were your parents willing to give you away, but it actually gave them some kudos in the parish. 'See that woman there. She has two daughters who are Poor Clares' or 'She has a son who is a priest.'"

But how did he manage to stick it for five years?

There must have been something that was philosophically appealing about it.

"It was annihilatingly boring. But that was never a reason for leaving. You see, they had the answer to everything. If you said you were bored then they would say: 'Look, anyone can cope with ecstasy, but the real question is how do you cope with boredom. When you feel bored or when you feel that you are in the wrong place then you know that God is testing you. Think about St John of the Cross, think about the great mystics, think of St Teresa of Avila. Remember her? She often used to feel alone and depressed. Remember how she used to cry out. "Where are you, Jesus. Where are you?"' They always had an answer. It's terrible really. I mean, just think of all those poor brides of Christ, all dying of loneliness and starving for affection and being told that God was only testing them."

People may not now recognise Tom's face as readily as they did in the days when he was playing Doctor Who, but they certainly know his voice. They know it from a thousand commercial voice-overs as well as from the spot-on impression of him in Radio 4's Dead Ringers. But most of all they know it from the huge television hit, Little Britain, where it serves as a surrealist introduction to the wonderfully grotesque sketches. I'm talking to him at a relatively isolated table but the sound of his voice has already caught the attention of several customers and I know that it will only be a minute before he'll be busy signing paper napkins.

"Let's stick with that monastery experience," I say with increased urgency. "I know that you now laugh about it but I wonder if it says something serious about your character. Over the years I've seen you embark on a number of projects which demanded a sort of self-immolation. Terrible masochistic self-defeating relationships with unsuitable women. I mean, look at you now. You dramatically sold up your house in Kent a few years ago and went to live full-time in an isolated part of France and yet I can't help noticing that you are now spending more and more time over here drinking in The George. Is France your latest monastery?"

"Well, it was a new adventure for me and the woman I'm married to. And this is our third year there. But two years ago I suddenly realised that I missed something terribly. I missed talking bollocks in the alehouse. I missed talking bollocks to wankers who only ever laughed at my jokes when I was buying the beer. I was missing the wonderful freedom of chaps in an alehouse. I was missing the very shit that I was running away from. There I was in south-west France amid the beautiful mysterious rolling countryside thinking that I would rather be in The George in Mortimer Street. That was very salutary."

But couldn't he go into bars in France? "I do go into bars and see all these old men in berets but most of the time I don't understand them. In fact I've recently decided it's easier to be handicapped. One day I couldn't see out of the window very well because of the rain and I started rubbing the glass. Then I heard an old woman tell her friend in French that I was probably nearly blind. And that's what I've now become. Blind. Whenever I go into this bar I pretend I'm blind and everyone goes 'Aaaah'. I spend minutes feeling around for my coffee. In fact I have eyes like a hawk for someone my age but somehow I've got stuck with playing a blind man. It's not like being with chaps in an alehouse."

It's when Tom is talking like this that I realise why I'm always pleased to see him. For years now I've been busily trying to turn myself into a proper bourgeois metropolitan man. I've come to believe that I genuinely like going to the theatre and posh restaurants and dinner parties. But I'm always sadly dispiritingly aware that however good the play or the food or the conversation I'd always always rather be up the road in a pub talking - yes - talking bollocks.

I suggest to Tom that what makes conversation in pubs so irresistible is its competitiveness. Every laugh and gesture of approval has to be hard won. Did he ever get an equivalent pleasure from acting?

"Well, I always found the stage terribly embarrassing, but after Doctor Who it suddenly became terribly easy because hundreds, perhaps thousands of people would come along to see the person who was on the television. I remember when I was playing in An Inspector Calls at the Theatre Clywd and hundreds of Scousers would come over to see me. And when I entered playing the mysterious Inspector they all clapped wildly and roared with laughter. No matter what I did or said they howled with laughter. They were absolutely determined to enjoy every second."

I've seen Tom on the stage several times. I missed An Inspector Calls but saw him playing Oscar Wilde in Chichester and have memories of the excellent performance he gave in the Michael Caine part in Educating Rita at the York Theatre Royal. But I've never really thought of him as an actor. As in Doctor Who, he always seemed to be peering round the side of any role that he plays. Neither have I ever heard him express much affection or admiration for other actors. What makes him so dismissive? "It's their willingness to believe anything they're told. I remember being at the National Theatre years ago and listening to the director, Roland Joffe, telling 25 or 30 actors that the wonderful play The White Devil was a play about eyes. And I watched them all write it down: 'This is a play about eyes.' And he could just as easily said: 'This is a play about knees.' And they would just as readily have written that down. They subscribe to absolutely anything."

"I've just been in a television series with Susan Hampshire, sort of Crossroads with kilts, and she said to me: 'Are you enjoying it.' And I said 'Yes. But then I can enjoy any old shite because I'm an actor. If you can't enjoy shite you can't be an actor.' And she said: 'Oh Tom, is there something about this part that makes you unhappy?' 'Yes,' I said, 'There is something that makes me terribly unhappy. What makes me terribly unhappy is that I am more interesting than the part I am playing.' That's why my great liberation was Doctor Who, because it was not an acting part. It was like playing one of those cult heroes like Sherlock Holmes. It's not really acting because those cult heroes are never supposed to change. They are predictable. They are always going to win. When I was playing Doctor Who millions of kids were stopping me in the street and sending me presents. They were sending them to me, to Tom Baker, because I wasn't acting. What they found interesting was Tom Baker. That gave me a great deal of confidence in myself."

It's difficult to imagine Tom Baker ever having lacked confidence. He may have just passed his 71st birthday but there's no sign of failing powers. He's big in every way. Broad muscular frame, large blue eyes, wide toothy smile, deep booming voice. Stir in a well-developed talent for disingenuousness and you have a combination that easily overwhelms most passing strangers and proves irresistible to close friends. "Good heavens, Laurie," he said, with wide-eyed mock amazement, when we accidentally met up in 2002 in Broadcasting House after a gap of over six years. "What a very clever idea! You've had your hair dyed grey."

But if I try hard I can just about remember the time when we were both together at drama school in the late fifties and he was having a difficult time. He was too tall to be well co-ordinated and he was also the only working class northern boy in a college stuffed with posh southern girls who were largely using the place not as a stepping stone to Hedda Gabler but as a passport to a commodity broker. I reminded him of those less confident days.

"It was all to do with what we were talking about before, with being brought up a Catholic. All Christianity is rooted in the ghastly premise that we are corrupt and we are not worthy. That really does have a profound effect. Being told over and over again that you are nothing. I remember in the monastery people walking around saying 'I am nothing'. That effectively turns you into a slave, a person with absolutely no sense of self-worth."

I can already sense that he's itching for a pint. There'll be no possibility of continuing a one-to-one in the pub so I bombard him with a few final questions. "What now delights you? Women? You used to have dozens on call." "No. What you saw a long time ago was a kind of madness. It just got in the way of absolutely everything. Michael Bryant, a wonderful actor and one of my very few heroes, once remarked: 'Standing cocks have absolutely no conscience and no brains either.'" "Men?" "No. I think I've left that a bit late in the day. I remember Francis Bacon once saying to me that he hadn't had a moment's happiness since they made it legal." "Your next acting part?" "No. I never have and never will take acting seriously. I have just been lucky. And the lovely irony is that my total lack of seriousness about the business has actually been finally confirmed by the fact that I am now entirely employed by children who once watched me from behind their sofa." "Religion? Any chance that you might go back to God as you near the end?" "No. I don't like any sort of high-powered commitment. I like low-key commitment now. That's what I have with my wife. I like that. Only the other day I suddenly realised that if God had had his wits about him and hadn't been so melodramatic then I might have stayed with him. But he wanted far too much. He overstated everything."