"It sounds like such a cliche, but it was therapeutic. I felt sad when I thought about sadder parts of my life, but it was still interesting."
Rob Brydon is explaining why, after a decade of enjoying recognition as one of the country's most popular faces and voices, he felt moved to put pen to paper and create his memoir of growing up in South Wales, and taking his first steps to success.
"I was on holiday a couple of years ago in France, and I started to write down some childhood memories just because I felt like doing it. And then when I got back, it turned out my agent had been told a publisher was interested in my autobiography, so the timing was spot on.
"It felt like the right time to do it in terms of having an audience, and it appealed to me in a way it hadn't in the past.
"One of the first things I did was construct a timeline, and I found that so much of the past... you have it there in your head, all jumbled up, but it's your own version of it.
"And then I became a detective getting in touch with old friends, and it turns out they remember a whole load of stuff I'd completely forgotten. I get interviewed quite a bit, so I tend to come out with a stock answer, but there's so much more in a life.
"It's made me look on anybody's autobiography in a different way, because you can only cover so much, in terms of aspects and angles, and since then I've remembered lots of other things too, about how I felt or thought, and it would have been nice to have them in there."
Brydon may feel there was more to say, but his book is already a big one, full of rich family anecdotes and friends of the sort you only make in short trousers and long summers. It describes going to the same school as Catherine Zeta Jones, but stops short of the crest of his success - he just says this felt like a natural place to stop. I wonder, though, if it isn't his natural good manners stopping him describing what would inevitably sound self-congratulatory: a catalogue of projects, from Human Remains, The Gavin and Stacey Show, I'm Sorry I Haven't A Clue on Radio 4, right through to The Rob Brydon Show and The Trip with Steve Coogan, that have all sealed his place in the country's affections.
It's a big body of work, and the pace sounds relentless. Indeed, the day I meet him, Brydon has just returned from Ireland performing in a theatrical farce opposite Kenneth Branagh, and has spent a sleepless night tending to a restless child. He is game - he even plays ball with an impression or two for me - but he is evidently flagging. Can he still laugh freely, now his jokes have become such valuable currency?
"It has changed, to a degree," he admits. "You're perhaps more economical with it, you have to conserve your energy a bit more. You try to choose your moments - it's not a bottomless well of ideas."
How does he stay fresh with so many people willing to drop buckets down said well?
"Variety is the answer. The thing I've just done, my first ever play, was the hardest thing I've ever done - learning 84 pages of dialogue, choreographed like a farce, and there's no leeway.
"When you're doing stand-up, you can comment if something fails, get a laugh from that. But with this, you can't just do your own thing, you're working as a team, so that brings with it a great pressure, which actors don't realise - they'd worry about the pressure of being on their own on the stage. But equally there's a pressure in not dropping the ball, which is really tiring, as well as physically demanding."
Not that Brydon is complaining. It took him longer than many of his contemporaries to break through the mainstream barrier, a doorway he reveals has its pitfalls:
"Human Remains and Marion and Geoff both brought awards, the chance to go on Parky, sell-out tours, so that was one level of fame, but it was all a little bit cult still, although I didn't realise it. That level of success is fine and dandy because the only people who know you like you. But then when you put your head over the parapet and have mainstream success with things like The Keith Barrett Show and Would I Lie to You?... suddenly, people are catching them without necessarily wanting to."
It's an interesting prism through which to view success, as a self-modulating thermostat which keeps people in check by exposing them to a wider audience than pure worship, an aspect of which Brydon seems keenly aware:
"Some people say about me, 'he doesn't turn anything down, does he? Terrible'," he explains. "You can't say this without sounding bigheaded, but I turn quazillions of things down every day.
"We're all grown-ups, I can take it, but it is different, you get noticed a lot more, which I'm not complaining about at all... the pluses far outweigh the minuses. There are some people who only know me for cornflakes ads, and that's fine. I have a charmed life.
"I think it's a mistake to moan, because I had years of struggling to get recognised, noticed, my phone calls answered, requesting to be in things, so I think it's unlikely I'll ever moan about it.
"Plus, I've always felt that, if the worst came to the worst in my career, I could always fall back to doing voices on the radio."
Ahh, yes, the voices, his uncanny channeling of everyone from Ronnie Corbett and Alec Guinness to his Small Man in a Box that kept Brydon in coinage for years on the wireless long before telly found him, and we saw him with Steve Coogan - his friend, mentor and sparring partner - trading syllable for syllable when it came to channelling Michael Caine in The Trip. (Interviewed recently, Michael Caine himself was most diplomatic, saying, "they both got it right.")
Such power of mimicry depends to a great extent on finding the space and peace to observe people for great lengths of time. Does Brydon's own level of recognition now interfere with that process?
"In theory, yes, but in reality, you can still observe, just by watching documentaries," he reflects.
"A lot of Human Remains was inspired by TV, and the equivalent of the Jeremy Kyle show, Vanessa, Trisha - we'd see people on there with very interesting character traits.
"Once you have a comfortable life, you tend to be surrounded by like-minded people, so it's not dissimilar from that. We wrote quite a bit of Human Remains in cafes, we'd just be looking around. I'll see someone on the street and I'll think I could look like him if I had a moustache. I do seem to look like a lot of people."
Rob Brydon's memoir, Small Man In A Book, is available now.