IF YOU'VE seen the scripts he's written and starred in, from the pop culture dressing-up box that is Spaced to his rom-zom-com Shaun Of The Dead, then you'll know the giddy eagerness of Simon Pegg.
Film fandom is something that runs through his most personal work like letters in a stick of seaside rock – and yet when he was offered the chance to sign up for science fiction's current franchise behemoth, as the Enterprise's first engineer, Montgomery 'Scotty' Scott, he admits that he hesitated.
When he says this I immediately assume the reason is that Pegg is famously an out-and-proud Star Wars devotee, and in the science fiction world the eternal rivalry between Star Wars geeks and Star Trek freaks is like the Crips and Bloods for nerds. In Spaced, his character even notes that all the odd-numbered Star Treks are rubbish. As it happens, Pegg stars in Star Trek 9.
"Oh no, I love Star Trek too," he says, horrified. "I watched it since I was nine. This was back when there were only seven or so, and it was a widely held controversial geek's eye view of Star Trek. But that's not true any more. I just really don't want Scotland to think I'm making fun of Scotty. And if I get it wrong, I could have blown my chances of being welcomed in Scotland ever again."
He's joking. A bit. Pegg's a natural worrier, and something of a perfectionist, but he was the only member of the cast who didn't have to audition for the rebooted and suited Star Trek. The film's director JJ Abrams, a Shaun Of The Dead fan who previously cast Pegg as a quirky supporting player in Mission Impossible III, simply sent him an e-mail that said: "Do you want to play Scotty?"
Pegg is so down-to-earth and keen to please that you sometimes forget that nowadays he has more success and therefore more clout than any other British comic actor, and most of his Star Trek colleagues. Pegg looks like a nice man from IT come to fix your computer. Yet it's nice, earnest Pegg who has the more impressive CV and a roster of influential fans.
Quentin Tarantino wanted him to appear with Brad Pitt in Inglourious Basterds, but Pegg couldn't find the time. While working on Mission Impossible III, he would entertain Tom Cruise by telling him about the film he was writing, Hot Fuzz. He's even godfather to Chris and Gwyneth Paltrow's oldest child, Apple, and appeared onstage last Christmas with Coldplay, on the harmonica. "At first I was terrified," he says. "I almost thought I would faint. But by the second night I found my feet and was telling jokes."
There are some signs of performance anxiety today as well, as he swings himself back and forth on the hotel couch. No matter how many times the series has been reworked in its 43-year history – from Next Generation to Voyager to Enterprise – no one has dared to take on the roles of the original cast before. And just as this Star Trek was no longer a home for aliens with knobbly foreheads and other sci-fi clichs, Scotty was also up for redefinition.
"In any case, you can't play James Doohan – that would be disrespectful to James Doohan and the character," says Pegg." So I decided to start from scratch and play a Scottish physics genius. My wife Maureen is from Glasgow and she was determined that Scotty would be West Coast, but I think he's from Linlithgow historically, so I started out a bit East Coast and I was told to bring it further west because Scotty is a bit of a brawler. And my father-in-law is a working class Glaswegian boy… and, in the end, so is Scotty."
Doohan, affectionately remembered up here for minting unforgettable Scottishisms such as "That'll put the haggis in the fire", died four years ago, and since this is a how-they-met Star Trek film, there was no logical way to bring any of the other old crew members into the new picture. The one exception being the original Spock, Leonard Nimoy, who has a cameo in this film and shares scenes with Pegg.
"In between takes we'd be sitting in chairs next to one another,'' says Pegg, who spent a week filming with the 78-year-old actor. "I was beyond excited, but I couldn't let on because I felt that everyone probably tells him how they feel about Spock.
"And the man's got a genetic dignity about him which meant I waited until our very last day together to tell him that it was very hard to have Leonard look at me and say lines and me not go: 'Whooo', become very excited, and need to go to the toilet."
The new film might reset Star Trek history, but it also resets Pegg's life. He has signed on to do two more Star Trek films, and as part of a blockbuster series there will be no more anonymous days in Morrisons for him. He's also finished shooting his role as one of the Thompson Twins in Steven Spielberg's 3D motion-capture version of The Adventures Of Tintin, and he enthusiastically pulls up a picture of himself on his iPhone showing him in a dark latex suit dotted with motion detectors to guide the animators.
"Everyone wore them, even Daniel Craig and Jamie Bell," he says. "And Spielberg was everything I hoped he would be."
The other Thompson Twin was his Shaun Of The Dead and Hot Fuzz co-star Nick Frost. In many ways, given his love of double acts, Frost is Pegg's artistic other half, as big and dark as Pegg is slight and peroxide blond. As flatmates, they even briefly shared a double bed, Morecambe-and-Wise-style. The night before his wedding in Glasgow four years ago, Frost and Pegg slept together one last time.
"It wasn't like one last fling," he protests. "Maureen was with her family and Nick and I were in my room watching videos and fell asleep together. It's not like we planned to have one last night for old time's sake!"
Even so, Frost and Pegg are about to get into bed again, artistically speaking, for Paul, their first script together since Hot Fuzz. They will play British sci-fi geeks who are going on a road trip from Comic-Con in San Diego to Area 51.
"As research, we got a motorhome and drove from LA to Denver last year," Pegg says. "And the script's definitely one of the best things we've done." Filming starts this summer in New Mexico, just as Pegg embarks on his most personal co-production, the birth of his first child. The couple have already made natal arrangements in America, although this probably means Pegg Jr won't be able to play for Scotland.
"No," agrees Pegg. "But it does mean they can become President of the United States."