First children's drama, next a pop career, then Ant and Dec made Saturday evening television their own with a string of mega-popular entertainment shows. Now they're venturing into film, starring in a UFO comedy alongside 'proper' actors. Michael Dwyer meets the ubiquitous geordies

ANTHONY McPartlin and Declan Donnelly had already spent more than half their lives in show business when they turned 30 within two months of each other last autumn. Unlike so many performers who started young, they sidetracked the path to excess, keeping their feet firmly on the ground and taking control of their careers as their collective star rose inexorably, presenting SM:TV Live, Pop Idol, I'm a Celebrity . . . Get Me Out of Here and Ant & Dec's Saturday Night Takeaway.

Ant and Dec are the face of Saturday night television in Britain, their appeal spanning across the generations. What you see is what you get with Ant and Dec, and they are just as engaging off-screen. They exude enthusiasm for their work, and their symbiotic relationship is reflected in the way they finish each other's sentences. Two minds think as one.

We met last week in west London's Ealing Studios, which provided all the interior sets for Ant and Dec's first star vehicle as movie actors. Alien Autopsy is a breezy light comedy inspired by a scam in which two Englishmen faked a documentary purporting to show footage shot at Roswell, New Mexico in 1947.

The duo are cast against type: Ant, the extrovert on their TV shows, wears glasses as the practical, sensible Gary Shoefield, while Dec is stubbly, scruffy and reckless as Ray Santilli, the mastermind of the hoax.

"When we read the script," Ant says, "we instinctively thought about playing the roles the other way round. It was suggested that we try switching the roles. At first we doubted that would work, but they liked it when we tried it, and now I couldn't imagine doing it the other way."

Alien Autopsy takes them back to their roots as actors in the popular BBC children's series Byker Grove. "We've always wanted to act again," says Ant. "For years we told ITV we'd love to do some comedy-drama or maybe a sitcom. We've been sent quite a few film scripts, but they never quite hit the mark. They were all very much in the style of Ant & Dec: The Movie - a bit like Spiceworld, if you know what I mean."

Perish the thought. "We never wanted to do anything like that," Ant insists. "Then this came through and it was exactly what we wanted. It's interesting, too, because it's a true story, which caused such a hullabaloo."

They were chuffed to be working with US actors Bill Pullman and Harry Dean Stanton. "To be on set with Bill was quite strange because he's a proper movie actor, whereas we were just pretending," says Dec. "But he was really generous to work with, and Harry Dean was just a legend."

Ant notes that Stanton was a bit grumpy. "He hadn't a clue who we were, and we didn't expect he would. Harry's quiet in the mornings because he likes his late nights, although he's brilliant on set. On our last night shooting in LA, he took us out to this little 24-hour drinking hole of his. It was just great sitting there with him, and everyone who came in knew him. It was a late night."

Alien Autopsy plays like it was written specifically with Ant and Dec in mind, but it wasn't, Dec says. "The director, Jonny Campbell, and his wife were watching I'm a Celebrity one night and she said: 'What about those two?' His first reaction was to say no way. Then he thought about it and wondered if we could fast-track that chemistry we have into the movie."

That effervescent chemistry stems from the close friendship between Ant and Dec since they met on Byker Grove when they were 13. They went to different schools in their native Newcastle, Ant to a comprehensive and Dec, one of seven children born to a couple who moved from Derry in the late 1950s, to a Catholic school for boys.

Achieving TV fame as PJ and Duncan on Byker Grove had its drawbacks when they were back in their classrooms.

"It was difficult to start with," Ant says. "You know what kids are like at that age. There's a lot of jealousy. It wasn't as if we'd gone to drama school and other kids would be pleased for you when you got roles. It was quite difficult with certain teachers, who were quite jealous, too. We were in our GCSE years and were taking time off school and we would have a tutor on the set."

"It was a great time, though," says Dec, "to be getting out of school and to be on telly at that age and to have a bit of money in your pocket." Maybe as much money as the teachers got? "Probably," says Ant, "but at 15, to get off school and to buy whatever trainers you like, that's all you want."

Did they get on well from the first day they met? "No, not at all," Ant says, to which Dec responds: "I thought he was just really miserable. He would sit in the corner and not say very much." Ant concurs: "I was really nervous and shy and didn't really speak to anybody. I came into the show on series two, and all the rest of the cast already knew each other. After a while, we started going to matches together because we're both Newcastle supporters. That's where our off-screen friendship started."

When they were 18, Ant and Dec experienced the harsh taste of rejection that comes with the territory that is show business: They were dropped from Byker Grove.

"We were having a great time," Dec says. "We were two of the most popular characters on the show and we were getting the most fanmail. We got called into the producer's office and he said sorry, but he was going to have to let us go. We were amazed, but he made the point that we were 18, and 18-year-olds don't hang around youth clubs unless they're a bit weird."

They had performed a song on the show, and a record company offered them a contract. Retaining the names of TV characters PJ and Duncan, Ant and Dec recorded 12 consecutive Top 20 hit singles between 1994 and 1997. Their biggest success was Let's Get Ready to Rumble, along with a Top 5 record, Psyche - The Album.

"That was it," Dec says, "the average shelf-life of about three years for a group. It was a great laugh. We toured the world, all over Europe and to the Far East and Australia. It was the first time we had been anywhere apart from Spain or Ireland. We had three amazing years, but it was always at the back of our minds that it wouldn't last forever. So we kept an eye on getting back on the telly at some stage."

As the presenters of the original Pop Idol, they sympathised with the losers, playing good cops to judge Simon Cowell's bitchy bad cop.

"That was genuine," Dec says. "It was the first show where the public got to choose and where the contestants were really brutally critiqued in front of a live audience. We felt a real affinity with them because we'd all done auditions. It's bad enough not getting the gig, but to get savaged like that in public is very tough. Of course, there were some awful acts as well. Celebrity will eat itself."

On that subject, they will return later in the year to present another I'm a Celebrity . . . Get Me Out of Here. They always stay in a comfortable apartment while the contestants eat worms and live in tents. And they are planning another series of Ant & Dec's Saturday Night Takeaway. For sheer entertainment value, there isn't a show to match its pace, exuberance and good humour, and the hosts have to set and sustain the crucial energy levels.

"You have to be totally wired," Ant says. "It's live, so you've got to be on your toes and just ready for anything. It's hugely exciting, a great adrenaline rush. It's our favourite show. As soon as it starts, it's like getting on a rollercoaster and there's no getting off till it's over. Whatever happens, you've got to go with it."

They've also devised The Con Test, a quiz show they will present over seven consecutive nights in July. The winner is guaranteed to take home £1 million.

"It's a question-and-answer quiz you can win without understanding any of the questions or knowing any of the answers," says Dec. "All you have to do is make everyone else think you do. It's a bluff, like a game of poker without the cards."

Ant says they got the idea from watching poker games on TV. "We thought of what would happen if we replaced the cards with questions and had the same kind of principle where you don't know how anyone else is doing and you've just got to make them believe you're doing very well in order for them to fall and for you to win the jackpot. We had a few dummy runs in a room over our local pub and it went very well. Then we shot a pilot and pitched it to ITV. They really liked it."

The concept - and the duo's Midas touch - should ensure another sure-fire ratings hit. Ant and Dec are, no doubt, millionaires in their own right, but they seem entirely grounded and unaffected by their rise and rise through the fiercely competitive ranks of show business.

"I think we're very lucky," Dec says, "that there are two of us and we've always got another opinion. We talk about everything and carefully consider every decision. I sometimes feel sorry for people who are doing this on their own."

Adds Ant: "We had a certain level of fame on Byker Grove over a period of years, so we dipped quite slowly into the fame game. It didn't happen overnight, so we had time to get used to it, which was good for us."

Is there a downside? Can they walk down the street?

"We can, quite easily," Ant says. "We get recognised a lot. The good thing is that most people leave you alone. They might come up and shake your hand, or give us a toot on the horn. There's a lot of goodwill towards us, which is really nice. People just think we're one of them. It's not like it is with, say, Robbie Williams and all that mass hysteria. Actually, one time when we were over in Dublin and shopping on Grafton Street, everyone was saying hello, but nobody was bothering us."

In keeping with their relationship with the viewing public who think they're "one of them", there will be no financial arrangement with any glossy magazine when Ant marries his long-time girlfriend, make-up artist Lisa Armstrong, in the summer. "We're doing it in private," he says. "We haven't signed up to any kind of deal. It will just be family and friends."

Impishly, Dec gets the last word: "Although the best man's story is available to the highest bidder!"

Ant and Dec will attend the Dublin premiere of Alien Autopsy at Cineworld on Wednesday night. The film goes on release from Friday next