It's a bitingly cold October day at Pinewood Studios, the current home of the Woman in Black (another Jane Goldman joint), First Class and Pirates 4, which has taken over the 007 stage for some fountain of youth shenanigans.

Empire has come here to witness one of the key moments in the film and, if you're onto your mutant lore, a momentous occasion in X-Men history: the birth of Cerebro. If you're not into mutant lore, that's the metal bucket that Professor X wears on his head to amplify his telepathic powers and find new mutant around the world.

It's a pivotal moment for James McAvoy, stepping into the shoes, if not quite sliding into the wheelchair just yet, of Patrick Stewart as the young Xavier, for this is where Xavier, to paraphrase Steve Martin in the Jerk, discovers his special purpose. "When we first meet him, there's quite a lot of swagger," says James (McAvoy). "He's quite pleased with himself, really. But when he uses Cerebro, he realizes that there are thousands, possibly millions, of mutants out there and they're really alone. That touches something in him. That makes him realize, 'I know what I need to do now.'"

Interesting theory, but putting in into practice is not so easy. The scene's been delayed for a number of reasons. Vaughn's initial plan to shoot the scene, which takes place in the circular lab of scientist Hank McCoy (Nicolas Hoult), against a reflective gold backdrop has been nixed, so there's been a last minute rejig to shoot entirely against greenscreen.

With that sorted, it gets underway. James (McAvoy), Michael – as the young Erik Lehnsherr – Hoult and Jennifer Lawrens (as the teen version of the shapeshifting Mystique) enter the lab. Hoult's Hank briefly explains what Cerebro is – "It's Spanish for brain" – before Xavier, eager to try it, walks over and lowers the bulky, analogue prototype festooned with cables and wires onto his head. "Are you sure we can't shave your head, Charles?" asks Michael. "Don't touch my hair," replies the egghead-in-waiting (that's one for the funboys) an then...

It all comes to a halt. It's a complicated scene. There are numerous practical elements involved, including a lighting change when James (McAvoy) plugs into Cerebro, and they're not all working in tandem. Combined with Vaughn's decision to cover the scene with a series of 360-degree tracking shots, it's clear that it's going to take a while. The actors remain on the set between takes, cut off from Vaughn and his video village by a giant greenscreen. We can hear them occasionally – James (McAvoy), a Big Back To The Future fan, dons the helmet at one point and yells, "1.21 gigawatts! 1.21 gigawatts!" in the best Doc Brown voice – but it's mainly murmuring and sniggering. Still, it's hard to detect an air of frustration when Vaughn giving James (McAvoy) some direction via loudspeaker, ask that the sound channels be kept open so that he can hear James's (McAvoy) response. Cue an intake of breath from Michael. "Ooh... dangerous!"

"Week 11 of the X-Factor shoot, and James is losing his mind," explains the disarmingly frank James, Big Brother Voiceover Man style, when Empire catches up with him. "It's like any big ridiculous super-budget movie. Anything that size can make you feel like you're going mad, so you have to try to remember that when you watch those films in the cinema, it's an escapist experience. Mind you," he laughs, "they're going to be making this movie while it's in the cinema!"

Ooh... dangerous.

First Class may principally be the story of Charles and Erik, how they come together as friends and found the X-Men, but other mutants are available, and when Empire next visit the set a couple of week later, they're out in force for a scene that take place near the end of the film.

We'll tread carefully in case the Spoiler Police are watching, but the scene sees Xavier, Erik, Hank, - now the blue-furred Beast we first saw played by Kelsey Grammer in the Last Stand –Mistique and newcomers Banshee (Caleb Landry Jones) and Havok (Lucas Till) plunge into battle for the first time as a team so newly formed that they're not yet called X-Men. They're en route in the X-Jet (designer by Hank) to thwart the diabolical plans of Sebastian Shaw (Kevin Bacon), leader of mutant menagerie The Hellfire Club, who wants to use the Cuban Missile Crisis to bring about a nuclear Armageddon from which a new mutant world will emerge and thrive. And yes, you did read that right. "I liked the idea of taking a piece of history and tweaking it," says Vaughn. "When you really look into the Cuban Missile Crisis, it beggars belief that the world nearly came to an end because of it. In a weird way, I think our history makes more sense!"

Vaughn's been looking to pay in the sandpit of the ‘60s for some time now. After Layer Cake he tried to get a film version of The Man From U.N.C.L.E. off the ground, unsuccessfully, while he "always had an idea for a Bond movie that would do the beginning of Bond in the '50s and '60s, and really recreate that stuff." Casino Royale – which Vaughn claims close to directing – screwed the pooch on that one, but it's clear that X-Men: First Class is giving him the chance to scratch an itch he's had for quite some time, It has gadgets galore, scantily clad girls as far as the eye can see and even a megalomaniacal villain threatening to blow up the world from the confines of his exotic submarine air. X-Men: First Class is Vaughn's Bond. And he's even got a 007.

"Fassbender is fucking Bond," says Vaughn. "if the Broccolis are looking for a replacement when Daniel decides to give it up, boy is he the obvious new candidate in my mind."