Casting the central roles was the biggest challenge -- finding actors in Britain who had the screen presence to strike that epic quality. "In the States, I think one of the reasons there are perennial heroes like Steve McQueen is because they're classless," says Merchant. "I think it's one of the things that are tricky in making British films, because class always comes into it. It's quite tricky to find something that feels neutral and allows you to think about the story and not the class of the characters."

"[Our actors] just had that," says Gervais. "They walked into a room and suddenly they were film stars. They weren't phoning their agent saying, 'I've got The Bill tomorrow and I've got a small part in Holby and I might do a play.' They were going, 'I want to be a film star,' and they got it straight away. Plus they were cheap, and we've signed up for 50% of their earnings until they're 68!"

If that's not strictly true, as we suspect it may not be, Gervais told RT last year that the plan was to extend the world into a TV series so the pair could further explore these characters, so this may not be the last time they work with the young cast. The spin-off is still on the cards, they said, but nothing was certain. "It's an option, but we never hold ourselves to anything like that. I'd like to, but anything could happen. We might think it ruins the legacy of the film, and that's important to us, and we'll turn it down. We might love it; we might do five series this time instead of two. I think the likelihood is that we'll probably write it, at least, because that's the real joy for us, the writing."

L to R: Felicity Jones as Julie, Christian Cooke as Freddie, Tom Hughes as Bruce, Jack Doolan as Snork.

"It's all speculative," agrees Merchant. "We've been totally focussed on this script. But we like the characters, and we'll be doing a scene with Ricky and we'll go, 'Wouldn't it be funny if...'"

"What we'd lose is the one big story," adds Gervais. "But we'd have more fun with the smaller characters. My character, for example - it could become about the family unit, so it's more of a sitcom."

For now though, the focus is on delivering the film amidst the pair's other commitments. In addition to their work together, Gervais, also has a stand-up tour to do (he'd probably be keen on us mentioning that it's sold out, as his last tour was) and his first American directorial feature, The Invention of Lying, to promote.

So with all the work on their plates have there been any tensions between them? "We see eye-to-eye on 98% of stuff," says Gervais. "And when we don't see eye-to-eye, we've got one rule: one veto and then it's out, or let's do them both and we'll see in the edit. There doesn't need to be arguments, really. And we work so fast, and it's such a joy. It's so much fun. The only thing I don't like is getting up early."

"Or doing the work," adds Merchant.

"Or doing anything."

"Anything that takes you away from the sofa."

Gervais unleashes that cackle again. "Yeah, so all my scenes were on the sofa. At one point Steve went, 'Ricky, are you actually asleep?'"

Cemetery Junction is released next year. Ricky Gervais' home on the web is rickygervais.com, where you can fail to buy tickets for his sold-out stand-up tour.