More details about Simon Pegg and Nick Frost’s forthcoming self-written comedy Paul were announced this week – most mouthwatering of all the revelation that the title character, who accompanies Pegg and Frost’s Brit geeks across America, is actually an alien.

But we weren’t satisfied with that, so we got Pegg on the blower and jabbed him repeatedly with pointed and probing questions, like some demented movie Paxman, until he spilled more beans.

“I’m very, very excited about it. I think it’s a bigger film than probably Shaun of the Dead and Hot Fuzz put together,” he said, before emphasising, “but it’s very much not the third one in the cycle. That’s reserved for when Edgar and I write together.”

That film, provisionally titled World’s End, is in the works, but Pegg is currently focused on Paul, which will start shooting next April in New Mexico, with Greg Mottola on board as director.

“I was a huge fan of Daytrippers, not to mention Superbad,” said Pegg, who’s been working on the idea with Frost for almost five years. “That’s why Greg sprang to mind, because he’s got a great indie sensibility.”

Pegg and Frost will play Graham and Clive, respectively – two British geeks on a pilgrimage to the San Diego Comic-Con. “They’re not the most confident guys in the world - Nick’s character is perhaps slightly more confident than mine, but they occupy the position of geek, you know?” said Pegg. “And their world is about to get a whole lot bigger.”

Cue the title character, who the two friends pick up while travelling across the Midwest in a hired RV. “He’s not your average alien,” teased Pegg of Paul.

At the moment, though, it’s not clear whether Paul will be an entirely CG character. “We’re figuring it out at the moment and having real fun, working closely with Double Negative who did Shaun and Hot Fuzz and Cloverfield and Hellboy II,” added Pegg.

“We’re looking to really work to find the best way to do it and to create something which is utterly believable and sympathetic and has gravity and presence and is somebody that you totally buy. He’s the eponymous hero, so he has to be amazing.”