Brilliantly bonkers comedy Mindhorn, starring Simon Farnaby and Julian Barratt, is released in UK cinemas today (5 May) and earlier this week, the writer-actors were knocking about in London in order to promote the film.

When IBTimes UK sat down with the pair, it's fair to say the funnymen were putting their comedic chops to good use, particularly when we asked whether they knew they wanted stars Simon Callow and Kenneth Branagh to make cameo appearances in the movie...

"Kenneth Branagh we had written in, almost from day one. He was almost the first thing we wrote down," Farnaby teased. "We just wrote Kenneth Branagh on a piece of paper and then tried to build the film around that."

So, what was the film they managed to ''build around'' Mr Branagh? Well, Mindhorn centres on washed-up actor Richard Thorncroft (played by Barratt), who once found fame playing small-screen detective Bruce P Mindhorn but much to his dismay, he never quite made it to the big time.

Luckily for Richard, he gets another shot at the spotlight, when he – or, more accurately, the character he used to play – inadvertently becomes involved in an actual murder investigation on the Isle of Man.

"The tax breaks..." Farnaby laughed when he began to explain why they chose the location. "No, that is only 50% true," he continued. "We wanted an island. We originally thought of Jersey but it's a bit too close to Bergerac and we didn't want people to think it's a parody of Bergerac, because it's not. It's many different things.

"But the Isle of Man was sort of perfect and the look of it, you've got these white washed walls and the three-legged insignia and the Laxey Wheel. It's a bit stuck in the past; a bit like Julian's character."

"It's quite 1980s," Barratt interjected. "We wanted it to be on an island that hadn't had a TV show on it like Jersey had. Like they were trying to make their own version of Bergerac and this is what it'd be."

Kenneth Branagh in Mindhorn
Filmmaker and actor Kenneth Branagh appears in a brief scene in Mindhorn, as does fellow thespian Simon Callow StudioCanal