'Computers make nice effects, but they can't bungee jump from a skyscraper'

He didn't mind whether he got to wear a cape or which evil villains in particular needed dealing with, he just wanted the special powers. He wanted to be able to climb tall buildings, he wanted to leap across roof tops and drive fast cars.

However, this was Sheffield in the 1970s and superhero was not among the list of possible job opportunities.

"Like most young boys I read comic books and grew up on a diet of Lee Majors in The Six Million Dollar Man and Burt Reynolds," he says, back in his home city after another gruelling filming schedule in LA. "I knew what I wanted to do from a really early age, but when I told my careers teacher I wanted to be a stuntman, they suggested I should perhaps have more realistic expectations. They said had I thought about being a fireman or a police officer. To them that was the next best thing."

To everyone else, Glenn's fall guy aspirations may have been just a pipe dream, but every opportunity he got he would take out his Hollywood stuntmen book a relative had bought him for Christmas and remind himself that adults don't always know everything.

He only wishes his old career teacher could have been with him a few months ago when he was on the set of Iron Man 2. As the regular stunt double for Robert Downey Jr, he finally got the chance to fulfil a few more childhood dreams.

"I actually got to wear the mask and the Iron Man suit," says Glenn, who, despite just turning 40, has kept his appreciation of the fantastical intact. "At one point I glanced at myself in the mirror and had to pinch myself.

"There I was on the same set as Robert, Scarlett Johansson and Gwyneth Paltrow, life doesn't get much better than that, does it?"

Few would probably argue and, having started his working life as an outdoor sports instructor for Sheffield City Council, Glenn has good cause to reflect sometimes on the journey which took him from the streets of South Yorkshire to Hollywood Boulevard.

"I've been lucky, really lucky," he says. "I've just happened to be in the right place at the right time."

It was a chance meeting while working as an instructor with a man charged with organising climbing sequences for action films that first set him on the daredevil path. They were introduced by a mutual friend and talk soon turned to stunt work.

"He told me there was an official stuntman register and everything fell into place," says Glenn. "I suddenly realised there was a very definite process I could follow to realise my dreams and from that day I never looked back."

Having satisfied Equity requirements by gaining the relevant certificates in everything from martial arts to diving, Glenn earned the right should he ever want to put stuntman on his passport. He hasn't as yet, but since being accepted on the register at the age of 29, he has rarely been out of work.

First cast as Joseph Fiennes's stunt double, he has gone on to appear in everything from Batman Begins to Casino Royale, a film that raised the bar on the 007 franchise. However, it was a phone call a couple of years ago that took his own career to a new level.

It was the production team working on the new Sherlock Holmes film and they wanted to know if he was interested in being Robert Downey Jr's stunt double.

"I'd just finished Quantum of Solace and was looking forward to have a couple of months off," he says, admitting he came very close to turning down the opportunity. "I was in France having a nice time and wasn't sure that I wanted to be back on set so soon, but when I heard more about the plans, I decided it was something I had to do."

The reinvention of Sir Arthur Conan Doyle's detective for the big screen was a hit and Glenn's high dives from the Parliament buildings and his ability to roll over barrels have not only earned him two nominations in this years Taurus World Stunt Awards – a glitzy Hollywood affair – but secured him regular work with Downey. Iron Man 2 is out at the end of the month and he's just finished shooting on Due Date due to be released later in the year.

"Robert is very keen to do as many of the stunts himself, but he knows his limitations," says Glenn, who bears more than a passing resemblance to the actor. "He's fantastic to work with and once you're in his circle he is incredibly loyal.

"Anyone who has seen him in Chaplin will now how talented he is and when I began working with him, I realised he has such a specific way of moving. Fortunately, I seem to be able to replicate that and because he likes to work with as many of the same people as he can, the last couple of years have been fantastic for me.

"Actors like stuntmen who make them look good. If you get on it's a bonus, but I honestly haven't got a bad word to say about Robert. He is just a really good guy."

Broken fingers and dislocated joints are par for the course as a stuntmen, but one serious injury aside, Glenn has emerged from each new film remarkably unscathed. However, he knows the dangers. He is friends with Daniel Radcliffe's double David Holmes who was left paralysed after falling from a harness while practising flying scenes during the

filming of Harry Potter and the Deathly Hallows.

"Not long after I started, I had a bad fall and ended up hobbling around for a bit and I'm still feeling the effects of Iron Man 2," he says. "In one scene, I was fired into a car and it didn't quite go how we'd planned it. My osteopath is going to be busy while I'm back here, but it's a bit like being a rugby player, injuries are unavoidable.

"These days, so much care is taken to ensure the stunts are safe. There can never be 100 per cent guarantees, but this is what we are trained to do.

"I guess the work we put in is why I don't get scared. I still get adrenalised, the day I don't have that feeling will be the day I stop doing it."

While Sheffield remains his base and much of his work has been in Europe, Glenn hasn't ruled out a move to LA and while his career has been spent turning ordinary actors into action heroes, he may yet be persuaded to take a more visible role in films.

In Quantum of Solace, he played Craig Mitchell, M's bodyguard and double agent. It was only a small part, but the few lines he spoke

before he dashed across the roof tops did give him a brief taste of acting.

"Who knows what will happen in the future, it might be something I explore," he says. "But if I'd wanted to be in the limelight, I wouldn't have pursued the stuntman dream, I would have gone into acting straight off.

"There's something nice about going to a red carpet premiere and no one knowing who you are. When you see the whole spectacle from a distance it makes you really value your privacy. As nice as it sounds, I'm not sure I'd want the kind of adulation someone like Robert attracts."

Glenn isn't quite sure where his career will take him next. There is already talk of a sequel to Sherlock Holmes, it seems unlikely the Iron Man franchise has yet run out of steam and while advances in CGI have made the previously impossible possible, the movie world will always need stuntmen.

"Whatever trickery you can do with computers, you still need a body to go from A to B. Plus audiences like their action to be as real as possible. Computers can make things look nice, but they can't bungee jump from a skyscraper."