How David Walliams recruited Sheridan Smith, Jack Whitehall and Harry Enfield for his first sketch show since Little Britain

Having spent the past few years writing books, judging Britain’s Got Talent and acting, he wanted to take things slowly. As an experiment, he worked with Joanna Lumley on a pilot last Christmas. “I’d done an episode of Marple with her ten years ago and the quality of her anecdotes is really good,” he beams. “I’m glad we got someone as classy as her – and as game. And, God, for a beautiful, glamorous woman, she doesn’t mind making herself look ridiculous, which you often don’t get.”

For the new series he’s recruited a different friend for each episode. It’s an impressive roster – Jack Whitehall, Sheridan Smith, Harry Enfield, Miranda Richardson, Meera Syal... and Hugh Bonneville for the Christmas special.

Unlike your typical “and friends” show, which usually involves agents ringing agents, Walliams really does have these people’s numbers. He’s known Meera Syal for ages and been round to dinner with her and husband Sanjeev Bhaskar. He met Miranda Richardson at a French and Saunders show – “watching it, not on it – and I tried to ask her out on a date. She wasn’t having it. But I really wanted to work with her, because she’s such a brilliant comedian.”

Harry Enfield as the Queen and David Walliams as a historian in the sketch Who Does One Think One Is?

He met Jack Whitehall making a show. “But he’s obviously a lot younger than me, and he went, ‘I used to love Little Britain when I was at school.’ I suddenly felt ancient.” He had the same thing in reverse with Enfield: “I grew up watching him and he was a huge influence. Little Britain is, basically, a version of the Harry Enfield show. He’s one of my idols. I’m in awe of him.”

He met Sheridan Smith at the Variety Club awards, “then we did A Midsummer Night’s Dream together in the West End,” he says. “We were together for about five months and you get to know each other really well, so I wanted to work with her again – especially now she’s much more famous and successful,” he laughs.

And there’s Hugh Bonneville who played Mr Stink in the TV version of Walliams’s book for children. “He’s really funny,” Walliams grins. “He threw himself into everything and didn’t mind making himself look stupid. We’ve got him in the Christmas special because he’ll appeal to people like my mum.”

Celebrity friendships are sometimes weird, he says. “There are people I’ve met – like Jimmy Carr – before we were both well known and we’ve always been good mates. I suppose really they’re work friendships. You can talk about the ups and downs of your job and living in the public eye and things like that. People in show-business are quite friendly to each other. When I’ve been to the Baftas with my mum she’ll go, ‘Oh, it’s Alan Titchmarsh. Can we meet him?’ I’ve never met him in my life, but I’ll go up and say, ‘Hi Alan. I’m David. This is my mum. She’s a big fan’ and he’ll be really nice to us. But, you know,” he laughs, “me and Alan Titchmarsh don’t go on holiday together…”

So who would he call in an emergency, if he had to bury a body at midnight? “If it was that, it would be Simon Cowell, because obviously he’s done a lot of that and I’m sure he’s got a team who can do it,” he laughs.

Cowell, the celebrity mate he’s most often pictured with, gets a gentle ribbing on the new show with a repeating skit about Il Prima Donna, a parody of Cowell’s classical boy band Il Divo. Il Prima Donna sing Prodigy’s greatest hits and football terrace chants in soft-focus videos advertising “music to make love to”.

“I thought I’d give them a plug because he must be short of a few bob.” Walliams smiles. “I’m always rooting for him to make another billion!”

That sort of teasing – “having fun with people” – is important in friendships, he argues. Which is why his favourite part of making the new series was messing about in rehearsal. “It’s like playing,” he shrugs. “I watch my nephews and my son play and it’s not a million miles away from being with other actors and mucking around with the script. I feel blessed to still be able to play. It’s so much more fun than writing books – which is lonely and demoralising and you’re often in tears.” His voice briefly drops, then he’s back. “But I wasn’t in tears writing this. I had a good time.”

Then our time is up and he has to dash. He hesitates, worried that he’s being rude but excited about where he’s going so blurts it out – “Amazingly, I’ve got lunch with Michael Parkinson! I met him and sent him some books for his grandchildren and he said, ‘I must take you out for lunch.’ So… wow. How did this life happen to me?

Walliams & Friend is on tonight, Friday 25 November, at 9.30pm on BBC1