THERE’S an expectant hush in Waterstones. The back of the store has been roped off, and a large crowd has gathered. Black-dressed bouncers politely discourage shoppers from straying into the roped off area.

Then a side door opens, and a small figure strides jauntily out. He gives a double-take, as if surprised at the number of people there, then launches into full Rob Brydon mode.

“Hello, book lovers!” he says, in that way he has that leaves you unsure whether he’s taking the mickey or not. “Hello, fans of signatures!”

He does another double-take for the benefit of Press cameraman Garry Atkinson. “Does my hair look great?” Brydon asks, acting up for the audience.

Then he sits down for the serious business of book signing: and he’s charm and warmth personified.

“Are you Katie?” he asks, of University of York student Katie Mason, who has shyly offered him two books to sign. “How are you Katie?” She admits she’s embarrassed at asking him to sign two copies. “I’m all for you buying two,” he says, drawing out the ‘two’ in that Welsh accent of his. “I’m not going to argue with that.”

Brydon’s in town to sign copies of his autobiography, Small Man In A Book. He’s on a hectic national tour that is taking him all over the country, for signings and evening live performances.

But you scarcely need to attend a live show, when he puts on a show like this for free.

Before he meets his adoring public, he has time for a quick chat in a private room upstairs at the back of the shop.

There’s more of that trademark deadpan humour. Is his funny routine just an act, or is he like this in private life too? “Ooh, I think if anything I’m even funnier!” he says. “I’m almost pathologically funny!”

Then he bursts into animated life when asked about Steve Coogan.

They’re great together in The Trip – the pair’s hilarious spoof TV series about a restaurant reviewer (Coogan) touring northern restaurants with a downtrodden friend (Brydon: very much Coogan’s second choice companion) tagging along for the ride. But does he ever feel he wants to slap Coogan.?

His eyes light up. “On a daily basis!” he says, that Welsh accent to the fore again. “Have we not all at some point wanted to put him over our knees, pull down his pants, and spank his bare, massive bottom! I know I have!”

As usual, you’re half tempted to believe him.

• Small Man In a Book by Rob Brydon is published by Michael Joseph, priced £20.