Interviewing a man who mystifies and manipulates for a living, you are, naturally, primed for a challenge, prepared for the tricks and techniques of evasion and suggestion that have made Derren Brown a household name.
From his first TV outings over a decade ago, in which he demonstrated his skills for sleight-of-hand magic and psychological manipulation, to more elaborate productions such as those in which he played Russian roulette live on TV and predicted winning lottery numbers, Brown has entertainingly demonstrated how people can be read and influenced, persuaded to believe in ghosts and conditioned to do anything from choosing a desired card to committing armed robbery. So I'm ready for any sneaky strategy.
"I waffle massively, by the way, and I apologise," he says politely, pouring peppermint tea. Oh, he's good. But he's going to have to do better than that sweetness-and-light act to get around me. The nice guy stuff, however, turns out to be no act. Brown totally confounds expectation. There isn't a sign of the uber-assertive performer who commands thousand-strong audiences at his live shows and bends individuals to his will on TV.
"I'm that guy while I'm performing, and I wouldn't necessarily want to know him," Brown says. "It's a controlling thing on stage - you're directing the action, getting people to play their role. In real life, I take being kind and nice seriously, so the last thing I'd ever want to be is that weird, controlling, manipulative character."
So he doesn't employ his techniques to win arguments, to get his own way and generally make people do what he wants?
"I'm probably more persuasive than the next person if I want to be, but do I want to be? In my head, I just don't go there. If you're a comedian, it's a bit of a choice whether or not you want to be funny when you're not performing because it might feel disingenuous. In the same way, I don't show people magic tricks in social situations any more. At my age, it's a childish route to impressing people and to need to do that is a sad thing."
This sweet diffidence may be strategic - the ultimate misdirection from a master manipulator - but Brown appears sincere. He describes his younger self as something of a loner and a precocious child who was part of the not-very-cool crowd. "My dad was a swimming teacher at the school I went to. I wasn't sporty and that was a bit tricky, I suppose."
That he describes his stage persona as weird is intriguing. What inspired him to become a performer?
"I had a natural aptitude for wanting to be the centre of attention and a definite skill for annoying people. In my first year at university [he studied law and German at Bristol], I saw a hypnotist perform and decided I wanted to do that.
"I was never at ease in conversations until I was doing magic tricks and if you don't feel impressive in yourself, you can do these things that make people say you're amazing. Performing took care of that obnoxious social urge, that neediness, and put it into a valid outlet."
His latest manifestation is Channel 4's Derren Brown: Miracles for Sale. In it, he trains a member of the public to become a faith healer before travelling with them to Texas in order to debunk what he calls a "disturbing, exploitative, disgusting scam".
By coaching an amateur in the techniques of suggestion and manipulation employed by those who claim to heal everything from arthritis to Aids - frequently contingent on a hefty donation - Brown exposes their venality.
As fascinating as Miracles for Sale is - and it is, as grim testaments to greed usually are - the programme is as interesting for what it says about Brown. It's a world away from sleight of hand and grand stunts, a foray into Louis Theroux territory. "Over the years, I've entirely grown out of the urge that got me into magic. I've pulled it into areas that I think are more grown-up and worthwhile, into areas that aren't about me going 'Ta-dah! Aren't I amazing!'"
Has he ever thought about giving up doing magic? "I think I would happily do the stage show and paint [a talented artist and illustrator, Brown used to submit his work to magazines - Radio Times included - before his career in magic took off ]. The stage shows are a delight - I like touring and putting on a good show with my
friends - but I don't enjoy the process of making TV. I never got stressed until I started making television."
Brown's interest in faith healing is made more interesting still by the fact that he was once an evangelical Christian - although he emphasises that debunking faith healing is about exposing scams rather than attacking religion. Inspired to attend Sunday school by a favourite teacher, it wasn't until his teens that he realised that not
everyone was a Christian.
"As soon as I got into hypnosis in my first year at university, my Christian friends' hackles went up and they talked about how I was ushering in the devil. I felt that if that was the insight and questioning going on, I didn't want to be a part of it.
"I read theology books and tried to undo all the pat answers I had for things, expecting to rebuild [my faith], but the rebuilding never happened. The first time I said to someone that I didn't believe in God, I felt a guilty rush but apart from that, it was liberating."
Given that he's gay, something that's still viewed with extreme intolerance by some evangelical Christians, Brown's faith is itself even more intriguing. "It was a convenient way of getting around not quite embracing the whole gay thing," he concedes.
Extraordinarily, he even got involved in the fringe evangelical Living Waters movement, which tries to turn gay people straight. "More interesting than 'Read your Bible and all your problems will go away', it had a bit of depth and psychology to it, but it was just based on a false premise."
This wasn't the only way that Brown sought to avoid being gay. "I wasn't denying it in myself but I had built up quite an austere, eccentric persona - I used to wear a cape, have long hair, that sort of thing. That's an easy thing to do if you're not relaxed about the whole sex thing.
"But when I got to my early 30s I realised that it wasn't going to go away and I didn't want to be that weird old man in the corner of the restaurant with the fedora, the big rings and the cravat."
Now, at 40, Brown is blissfully happy in a relationship. His eyes light up when he talks of his partner.
"I spent a lot of time thinking about me and working on what I wanted to be before I came into a relationship. In some ways, it's bad because you come into relationships quite late without a lot of experience and you have a lot to learn. But that can also be exciting. Certainly, it's lovely to have somebody love you and it's lovely to love
No longer projecting an austere persona, feeding a neediness through performing, or avoiding himself via a variety of means, Brown is great company and entirely at ease with the world. After much cajoling, he reluctantly concedes he may be "a joyful sceptic".
"I'm definitely not a cynic," he smiles. "Atheism gets seen as joyless and aggressive, as if not believing in fairies somehow makes you a misery. There's a Douglas Adams quote: 'Isn't it enough to see that the garden is beautiful without having to believe that there are fairies at the bottom of it too?'
"If you start talking sceptically and say that you don't believe in ghosts or God, people go, 'So you think we just live and die and that's it?', but I have a problem with that word 'just'. How does 'just' come into that? There is so much that is so extraordinary about life."