Funny business: Rob Brydon on the ups and downs of life as Gavin & Stacey's Uncle Bryn

So, off to meet Rob Brydon, actor, writer, comedian – yes, there are still a few around who aren't Michael McIntyre – and, of course, everyone's favourite man-child, Gavin and Stacey's Uncle Bryn.

Uncle Bryn is brilliant and I'll tell you for why: he just is! Favourite Uncle Bryn quote: "I've just checked the MySpace. I've got 17 friends... I'm snowed under." Second favourite Uncle Bryn quote: "If I was at home, I'd have some Nesquik." I could amuse myself like this all day. Third favourite Uncle Bryn quote: "Gavin, you're fired. Not really, I don't have that sort of power." I can fill the page without having to do any work! I don't even need Rob to turn up! Fourth favourite Uncle Bryn quote: "Now, you've probably never seen one of these... it's called a SAT NAV." Ah, here's Rob. Damn. Still, a quick one for the road? OK, fifth favourite Uncle Bryn quote: "Mint Baileys. What will they think of next?" If you watch Gavin and Stacey – the last episodes of which are screening over Christmas, bringing to an end one of the greatest sitcoms of all time – you will know that this is funny, and if you don't, and are feeling rather left out, you have no one to blame but yourself.

We meet in one of those cool Soho members' clubs, where the floors are wooden, the chairs are vintage chic, and all the members are sitting around, poring over laptops and striving to look important, even though they're probably only doing an Ocado shop. Whatever, Rob arrives looking spectacularly dapper in a Savile Row, Richard James suit, which is most disappointing. I'm not so dumb that I expect Rob Brydon to be Bryn ("It means hill in Welsh!" – sixth favourite Uncle Bryn quote) but, still, he could have made more of an effort and worn those "easy-care" beige slacks. They are non-iron, right? "I don't know, is my answer," says Rob, giving his answer. "I do think he'd be quite meticulous and I did want him to have the sort of light-coloured clothes retired men wear. They're impractical for any manual labour but perfect for popping across the road to chat with Gwen, and coming back home in time for Countdown."

Was Uncle Bryn fully formed in the script from the word go? "I'd love to say it was all due to my towering insight, but the show is awfully well-written [by Ruth Jones and James Corden, who play Nessa and Smithy]. Tight, economic, sparse, and the characters they've created are amazing. My favourite is Dave Coaches. He's got some lovely moments."

Sorry, have to ask this, if only because people will otherwise wonder why I didn't: what did happen on that fishing trip? He says he absolutely cannot say. "If I were to let anything out, Ruth and James would hunt me down."

We settle at a (wooden) table. He is 44, has a long face, and is sometimes mistaken for Strictly's Anton du Beke, "although Anton does have a bigger forehead". He has scarred skin from the bad acne of his youth. Did you spend your teen years lathering away with Clearasil? No, he says. He was put on antibiotics. "Clearasil was kids' stuff. I was beyond the Clearasil stage but, hey ho, I was blessed with the ability to be funny and that goes quite a long way." Do you like the way you look? "I'm a very, very handsome man, and have had to come to terms with it... um, do I like the way I look? In the right light, and with a following wind." I think you have a lovely face. "Thank you." Just like Anton du Beke's. "I think you will find he does have that bigger forehead."

He is really quite short, but then so are most of his heroes, like Ronnie Corbett and Dustin Hoffman. He doesn't know if the three of them will ever go on the razz together but, if they do, it won't be to Thorpe Park.

Rob first attained fame nine years ago in BBC2's Marion and Geoff, playing Keith Barret, the tragically cuckolded mini-cab driver, and since then the work has just kept coming and coming: further dark comedies (Human Remains); films (A Cock and Bull Story); panel shows (Annually Retentive); stand-up; tours; voiceover work (he was once the voice of Toilet Duck, but never the face, which might have been too much); Gavin and Stacey; and now the DVD, Rob Brydon Live, £28.99 (it's not just Michael McIntyre who has a DVD to sell). He says he has only ever done a normal job for one day. He was in his twenties, times were lean, and it was telesales. Soul-destroying? "It was environmentally friendly industrial cleaning agents and you were given a script and you had to try and make a connection at the other end, so if the person said 'Dusseldorf', you'd say: 'I had my honeymoon in Dusseldorf. I love that town!' In the interview for the job I felt such self-loathing it had come to this, that when this perfectly friendly little guy said: 'Tell us, Robert, do you have any hobbies?' I said: 'Yes, I keep rabbits.' It was a way of sticking two fingers up and the bloke was so sweet he said: 'Oh, really. Tell me about that.' I felt awful. He was only doing his job."

Rob Brydon is often said to be the nicest person in showbusiness, although I don't know where that leaves Cliff Richard. Out in the cold, I suppose. But Rob can be touchy, can put those two fingers up. I might ask him the most innocuous question – "Is doing voiceover work as lucrative as they say?" – and he'll come back with: "I can see where you are going with that!" rather as if I'm out to get him, which I'm so not. It's only an occasional thing – a flash – but it is there. At one point I ask him something equally innocuous and he says: "It's going to be quite a revealing answer, isn't it? Well done you!" And he keeps chastising me for being obvious – "Well, that would be the obvious interpretation..." – as if I didn't know! I do wonder if he's caught between playing the PR game – doing the interview, putting on the silly Santa hat for our photograph, flogging the DVD – and hating himself for playing that game. That said, it could just be that I simply bored him to death. This is perfectly possible. I once interviewed Lionel Bart and he fell asleep.

He's a south Wales boy, from Port Talbot, and always wanted to perform – so he never bothered academically, and did miserably. He initially only got two O-levels. "Maths was a two-part exam and I once didn't go for the second part. I knew I'd done so badly on the first it was hopeless. I re-took it about four or five times. I think I eventually got it by getting the top GCSE grade." You're a smart guy, and yet none of it interested you? "I didn't have the curiosity for knowledge I have now. The other day we went to have a look at some sixth forms for my eldest girl (he has three kids by his first marriage, and a baby boy by the second) and we went to one place and the history teacher there was outlining the syllabus. It was fascinating! I contemplated getting his number and paying him to come to the house once a week to teach me." Does he regret his lack of education? He does. "I think I've become more aware of what I don't know. I remember, when I did A Cock and Bull Story, I sat with Dylan Moran and Stephen Fry and they were discussing some historical event and there was nothing I could offer to the conversation. Absolutely nothing other than, perhaps, a humorous re-imagining of one of the principal characters and I thought: this is dreadful."

He attended a private school in Swansea until he was 14, when his family moved to Porthcawl and he went to the local comprehensive there. Gosh, did you get beaten up? "That would be the obvious interpretation," he says, which is fair enough, but did you? Get beaten up? He did not, he says. "I thought it was going to be like Grange Hill, and it would be a very savage environment, but I settled in after a week or two, and it's where I really knuckled down with the drama."

It's also where he first met Ruth Jones, a fellow pupil. "Ruth and I did a musical every year. So, with her, I did Sweet Charity, West Side Story, Guys and Dolls and Carousel and I loved them. That was my life, really. That was what defined me." I'm thinking that, back then, you and Ruth never imagined you'd one day have a number one with Tom Jones, as you did with "Islands in the Stream". Am I right? I am, as it goes (well done, me!). "The problem is," he says, "when I talk about that, I just gush, gush, gush. Ruth and I had the time of our lives. We were constantly pinching ourselves, constantly looking at each other, and saying: 'Can you believe what we are doing?'"

There was a spell at drama school, a spell at BBC Radio Wales, and then he came to London where the acting work was less than forthcoming so he took a job on a shopping channel. What did you sell? "You name it, I did it." Like what? "Name it, but don't be deliberately obtuse now." Dustbusters? "Yes, and lawn mowers and jewellery and bicycles and electronic keyboards." Were you good at keeping the patter going? "I was very good at it. I was told I was the best." Was it well paid? "By my standards, yes. It was better than working at Greggs." And is doing voiceover work as lucrative as they say? "I can see where you are going with that." Where? Where? OK, what's the best voiceover work to get? "Toilet Duck is a good one to get, but you don't want the prestige products. How many people are buying BMWs compared to how many people are buying Flash? You want toilet cleaner, shampoo, stuff people advertise a lot. It's all very well being the voice of Swarovski diamonds but I don't think they do a great deal of advertising during the Coronation Street ad break. I'm dong Sainsbury's at the moment. It's just a very nice, friendly voice."

And of all the work you've done since, what's the one thing you would want to show someone who had seen none of it? This is when I get: "It's going to be quite a revealing answer, isn't it? Well done you!" Then it's: "Showing for what purpose?" That's for you to decide. And you can't include the porn. "Ha, ha... slightly too loud, that laughter... but if I could show someone one thing. To impress them? To say, this is my art, this is what I'm better at that some other people? I really like the scene with Joanna Page [Stacey] in the back of the wedding car." When Bryn reads out her late father's letter? "I could picture my own children when I was saying it, which is why I fill up. I'm really happy with what I did there. There is something quite naked and honest about that scene." He wants to be taken seriously as a serious actor, I think, and why wouldn't you? Bryn is a brilliant character, but Rob is brilliant at being him.

Anyway, our time has run out, so we wrap up and part on the street, where he shakes my hand and says: "I might not be so friendly next time we meet. Let's see what you write," which is a little bit spooky. I'm just saying there is stuff going on here that sometimes jars with the loveable persona, and which probably makes him more interesting than he'll ever reveal. Still, no need to dwell on all that. And there is always my seventh favourite Uncle Bryn quote to cheer us up: "Welcome to my state-of-the-art multi-fitness studio. It's the talk of the street!"

'Gavin & Stacey' is on BBC1 on Christmas Day at 10pm. The final episode will be broadcast on New Year's Day