Imagine your foolhardy teenage exploits replayed on the big screen, those youthful aspirations cruelly contrasting with old friends who surpassed them.

Now you might get a sense of how journalist Neil McCormick feels watching Killing Bono.

For while McCormick might now be a respected rock critic with the august Daily Telegraph, his memoir I Was Bono’s Doppelganger has been filmed, with a new title actually suggested by U2 frontman Bono himself.

So watching an albeit semi-fictionalised account of his early ambitions of rock and roll immortality alongside a schoolfriend who actually achieved it must be a peculiar experience.

“It’s deeply traumatic,” chuckles McCormick. “This is a depiction of my failings exaggerated to the ‘nth’ degree. Sometimes even looking at yourself in real life on a tv screen can make you want to crawl out of the room, but seeing an actor magnifying your failings is really humiliating.”

Initial qualms that any of us might have felt soon gave way to admiration for the work of director Nick Hamm and stars Ben Barnes and Robert Sheehan who play brothers Neil and Ivan McCormick.

“The second time I saw the film I realised it’s pretty funny and what an amazing job they’ve done,” the author adds.

“And the best of it, I suppose, is being played by Ben Barnes because of course I did look like Ben when I was that age!

“Nick kept us apart and for the first six weeks of filming. Ben wasn’t allowed to meet me and he wasn’t really supposed to base his performance on me, so what was kind of shocking to me was the number of people who knew me saying, ‘God, he’s got you nailed’.”

Even though Bono casts a mighty shadow across the piece, a benevolent rock Titan whose genial good humour is conveyed in a fine portrayal by Martin McCann, Neil and Ivan are engaging characters too. They possess a strong bond of fraternal love too.

Although they lurk only in the background of the story, U2 are an integral part of it, with director Nick Hamm having enjoyed fruitful discussions with band members and their representatives.

“My relationship to them has always been incredibly close,” says director Hamm, “from both a management standpoint and sitting with The Edge and talking to him about it.”

The enigmatic guitarist, born David Evans, was – like his three bandmates – an old pal of Neil McCormick. But director Nick Hamm reveals he had a less than helpful casting suggestion of his own. “He wanted to cast Danny DeVito as Bono,” he chuckles.

With friends like that you can understand that Bono was more than willing to have a laugh at his own expense – and indeed come up with the title for the film.

U2 have given the finished film their blessing, happy with the journey it represents for their old schoolfriend, but perhaps also nostalgic for the world it recreates – as well as its offer of an abiding reminder of where they have come from.

“You know,” says McCormick, “every part of U2’s journey has been recorded except for these early days. They liked the film and they’ve given it their blessing. They want it to be a success.

“You know, it’s not their movie, they’re not standing in front of it and I think that’s good because it shows them from a different perspective – my perspective.

“And from there I see that, whatever idea people have about Bono, he’s a good guy doing good stuff and – as it turns out – a much better rock star than I ever would have been.”