Luke Treadaway: Rock 'n' roll actor with all the right connections

Luke Treadaway, 26, is the star of You Instead, a new rock 'n' roll romcom about two feuding pop stars accidentally handcuffed together for 24 hours at a music festival. Treadaway made his screen debut in 2005 in Brothers of the Head, in which he plays the singer of a band who is conjoined to his real-life twin brother, Harry. So being attached to his co-star is not a new experience for him.

Filmed over four-and-a-half days at Scotland's T in the Park festival in 2010, You Instead mixes in live footage to give the film an authentic feel, with plenty of action set against a backdrop of mud, portaloos and thousands of people partying. "There is a whole load of reality going on in the background, so it has this documentary look to it but it's also got this romantic comedy storyline running through it," says Treadaway. "But hopefully you believe these are real people in real situations as well."

Treadaway plays Adam, the heartthrob lead singer of a Californian electro-pop duo called The Make, who is handcuffed to feisty girl-band member Morello, of The Dirty Pinks, played by Natalia Tena, (witch Nymphadora Tonks in the Harry Potter films). A prophet fastens them together after a row at the start of the film to teach them a lesson about love.

For Treadaway, this is a far more light-hearted part than his role as a conjoined twin for Brothers of the Head. That must have been a claustrophobic experience. They were joined by harnesses and prosthetics – including a five-inch bridge of material that linked their chests – for their roles in the rock band The Bang Bang.

"It was both amazing and terrifying for our parents at the premiere," recalls Treadaway. "They had to watch Harry and I joined together and tear each other apart and go down a dark spiral of drink, drugs and depression. I think it was quite hard for them."

In his latest film, his character and Morello are at each other's throats and tensions run high, especially as both are with their partners.

But by the time they fall in love – Adam, with his shades and flying jacket, and his co-star, with her queen-of-cool boyish manner – it is clear this is a feelgood film, especially when she surfs through the crowd to meet him on the main stage. "It's not an original story, two people being antagonised by each other while trapped together in a situation and then realising they have a lot more in common than they think. But what makes this film unique is that it is set against a genuine backdrop of a music festival," says Treadaway. "It looks like I'm performing to 80,000 people because of the way it is edited, but really it was just to a field." They were even allowed to film the handcuffed pop stars storming the stage to ask the crowd for bolt-cutters during a genuine soundcheck for The Proclaimers' performance. "After that I had festival-goers coming up to me saying, 'I know you! It's Adam of The Make!'" says Treadaway. "They didn't know we weren't a real band but happy accidents like this were kept in."

Charlotte Cripps

'You Instead' opens nationwide on 16 September