Very odd to meet them in civilian clothes, this mismatched duo so familiar to us in assorted and elaborate costumes, wigs and make-up. Matt Lucas, pink-domed and solicitous, jeans teamed with the jacket of a Gieves & Hawkes suit, is the more outwardly friendly of the two. Or is it just that polo-shirted David Walliams’s vertiginous cheekbones and feline eyes give an impression of a mind working, judgments being made and stored away, when actually all is benign? Whatever, at 9am and in this prelude to what for them is one more day in an autumn-long, brainstorming-and-writing stint (preparation for their first live tour in eight years, followed by a West End theatre residency), breakfast is the pressing concern.

Once it’s ordered, they sit back to agree that yes, these are weird times. Suddenly, paparazzi are waiting outside their nearby office, for instance. “But where’s the value in pictures of us emerging to walk down the road?” wonders Walliams. “If a car suddenly mounted the pavement, yes, but otherwise those photos will never be seen.” Yet he, a single man in recent times linked with a Colin Farrell-worthy list of famous women, appears more comfortable with the degree of attention generated by our current collective love affair with their comic creation, Little Britain, than does his collaborator, who also lives nearby, but quietly and with a male partner. “Personally, I wouldn’t mind if I were never photographed as myself ever again,” admits Lucas, speaking to his cutlery and place mat.

Both feel they’re experiencing what might well be a once-in-a-career degree of attention and affirmation. “It’s like driving a car when the brakes have gone,” says Walliams. “You’re still steering, but you’re not in control any more. The programme’s not ours now. Once your inventions are being quoted in schools and offices, they have a life of their own, independent of anything you might do or say. This level of success has far exceeded our expectations, but what I’ve realised is that it’s not us who’ve made it a hit – it’s the public. Once they like and start talking about something, a certain magic happens. And it might never occur again in our lifetimes.” They’ve even inspired their own tribute act, Littler Britain. Notes Lucas, “They seemed quite good from what I saw on Richard & Judy.”

What those impersonators are thriving on (like the rest of us, in our water-cooler moments) is a cast of characters who are distillations/magnifications of the fellow citizens we each of us live among or even, perish the thought, of ourselves. Cheerfully absurd, occasionally grotesque, they include Lucas’s brazen Vicky Pollard (her catchphrase opener “Yeah but, no but...”), already a media shorthand for teenage ASBO-magnets nationwide; Walliams’s totally unconvincing, Edwardian-themed transvestite Emily Howard (“I’m a laydee!”); the respective two of them as bogusly wheelchair-bound Andy (“Yeah, I know”/“I want that one”) and his well-meaning carer, Lou. They are loved, the two of them, for having come up with this unusually vivid, of-the-era portfolio. “The public like the show, but I doubt they actually care that much about us,” corrects the cautious Walliams.

Their respective mums are loving the stardust-sprinkled aspect of their sons’ success, however. “It’s nice seeing the excitement it brings your family,” admits Walliams. “You can’t be cynical about things when you see it through their eyes. I took my mother to the Baftas, and introducing her to everyone was a real pleasure, because no one’s going to be rude to your ma, are they? What was funny was that she expected me to know everyone in the room. ‘Introduce me to Stephen Fry,’ she said, and that was fine because I’d met him before. ‘And Jonathan Ross,’ which was also OK because we’ve been on his show. But, ‘And now Alan Titchmarsh…’ There was no reason for him to know me from Adam, but I ended up chasing him up the stairs and saying, ‘Excuse me, but could you talk to my mother?’ which he did, and very, very nicely.”

Yes, but Diana Lucas and Kathleen Walliams are also made uncomfortable by Little Britain’s edgier elements – the character Jason fancying his mate’s nan, for example, or the Bitty sketches in which Mrs Proctor (actress Geraldine James) publicly breastfeeds her grown son, Harvey. Asked if a parental censor sits on their shoulders, protesting “But you can’t write that!”, Lucas nods vigorously. “Emphatically, yes,” he says, “but sometimes you’ve got to ignore them. Strands of the show are supposed to have shock value, like the Vomiting Ladies, or something in the third series I’m not even going to tell you about. My mum loves the VLs [Judy and Maggie, twin-setted bigots who throw up with force when confronted by anyone whose class, colour or sexuality they disapprove of] until that moment when they start to vomit, but that’s the whole point of the characters, isn’t it?”

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