OK, so you've seen some of the climbing action in Mission Impossible 2 and thought: how ridiculous! Nobody climbs like that!

So here's the low-down, brought to you exclusively by UKClimbing. Some fast facts:

• Yup, it really is Tom Cruise in those pictures
• Actually, he can climb a bit
• They know people don't really climb like that (well, apart from speed soloists like the US's Dean Potter, who has done El Cap unroped)
• They really were outdoors - no back projections
• No routes were harmed during the making of this film.

So let Earl Wiggins, an experienced cameraman who worked on the film, take up the story.

"We filmed at Dead Horse Point in Utah. Ron Kauk was the climbing stunt double. He and Tom got to be quite good friends during the week of shooting. Tom has a strong interest in climbing and is really fun to work with: tough, athletic, coordinated and aggressive. Ron worked with him to get him comfortable on the rock and so far off the deck - we were working at the top of the cliff, which is about 600 feet to the talus slope and another 2,000 feet to the river."

The sequence, which begins the film, shows Ethan Hunt (that's Mr Impossible to you, mate) on holiday. He's climbing, solo of course. Then it all starts to go wrong. Helppp! Cue dramatic deadhangs, dynos, etc. None of which you'd do in that situation without something very rope-like to keep you back from eternity. You can see the trailer if you're patient enough (it's a vast download) at the Mission Impossible site.

Earl says: "During filming, Ron would escort Tom into position and then get clear for each shot. We used winches to get Tom in and out of position. The rigging entailed cantilevered trusses on the rim to direct ropes.

"Tom did all of the climbing except the slip off the overhang - his main stunt double, Keith Campbell, did that stunt. Tom was on the cliff parts of five days for the filming and never complained which is rare for a big star. The climbing was choreographed by the film's stunt coordinator, Brian Smrz, who is arguably the best in the business. However, the choreography was inclusive of several elements that [film director] John Woo had felt were essential. The crucifix position is, I am told, in every John Woo film. I can't say if that is actually true but it was important to John. The leap sideways was also important."

So what about the fact that nobody really climbs like that? Don't tell Earl, he knows already.

"Of course we're being chided by climbers for not having a realistic climbing sequence. What climbers don't realize is that climbing is not a very exciting spectator sport, and nothing is more boring on film. The sequence as it is shown is exciting for the audience and sets the stage for Tom's character for the film. Also, nothing else is believable in the film so why should the climbing be? It achieves the goal of making Ethan Hunt look studly, gives the audience a sense of danger and provides great vistas for the revealing of the mission. As Anthony Hopkin's character puts it, 'This isn't mission difficult, it's mission impossible.'"

But if it was Tom C up there, how did he do those daring leaps without a rope? John Woo, the director, said he didn't want to look in the viewfinder because he was so scared each time that something would go horribly wrong but "Tom insisted on doing it". We take that with a pinch of salt (guaranteed to dispel hype). Even so, Earl says it's TC up there. So, how?

"Tom was on either cables or ropes at all times which were then CGI removed to make it appear he was soloing. We kept a minimum breaking strength of 8,000lb on all his equipment. The crew were tied in any time they came within 15ft of the edge. Cameras were on boom arms from above, helicopter mounted and I shot from on rope next to Tom.

"The bulk of the footage that appears on screen was shot from the helicopter using a SpaceCam mount. This is especially tricky flying where the camera operator and the pilot both create the shot and have to team together to compose. At times the helicopter was within spitting distance of us on the cliff."

And did all these safety measures mean damaging existing routes? Not at all, Earl assures us.

"We were not on a climbing route but at an area that other filming has taken place. Filming climbing and doing climbing are very different beasts. We try never to film at true climbing locations due to the [environmental] impact. Although desert sandstone looks terrible, it is actually quite safe to work on - the bolts are bigger in diameter and more frequent. Depending on what we are rigging, we will go up to bolts that are 3/4" diameter and 12" in length."

So now you know. Now head off and bore the pants off all your mates... or just enjoy the film.

And finally: we hear that Tom Cruise has bought the film rights to "Touching The Void", the Joe Simpson epic. Which should at least solve the problem of whether anyone would really climb on a mountain without a rope....