Is Sacha Baron Cohen a comic genius or a man running out of ideas?

Sitting somewhat uncomfortably on the sofa on a British chat show, Sacha Baron Cohen admitted to being nervous about appearing not as one of his repertoire of characters, but as himself.

“Terrible decision,” he said. “It feels bad. I’m regretting it.”

This is the man who in 2004 famously addressed the students of Harvard University as his streetwise creation, Staines native Ali G: “I is a bit nervous speaking to so many of you,” he said to an audience of the bemused elite, “at least me would be if I weren’t totally mashed. Normally the only public speaking that me does is to 12 people and it’s well easy: all me has to say is me name and the words ‘not guilty’,” he gleefully announced in his famously mangled blend of patois, accent and invective.

It’s reminiscent of Peter Sellers, who once marched onto Michael Parkinson’s show in a greatcoat and German coalscuttle helmet. He couldn’t just be ‘Peter Sellers’ and sought protection beneath a carapace of falseness.

Londoner Cohen, 44, has been rather more proactive then Sellers – forever remembered as bungling Inspector Clouseau in rather too many mediocre Pink Panther movies – since he has deliberately retired some of his characters.

But if Ali G and Borat Sagdiyev have been consigned to history then that leaves room for Liam Gallagher lookalike Nobby Butcher, the indolent wastrel of Grimsby for whom family – he has 11 children, a plus-size girlfriend and a long-lost brother to whom he has created a shrine in his shambolic home – is a defining aspect of his life.

Cohen’s genius for creating characters that sit outside the established parameters of social acceptability makes him a British contemporary of Mike Myers (aka Wayne Campbell, Austin Powers, Guru Pitka) and Ben Stiller (aka Derek Zoolander, Greg Focker).

Perhaps Myers represents Cohen’s closest comparison. The TV success of Wayne’s World led to two movies followed by three Austin Powers adventures, the emergence of Shrek and then the crash-and-burn of The Guru, described by some as arguably the worst film ever made.

Cohen attempted to follow up Borat (which was Oscar nominated as best adapted screenplay) with Bruno, the gauche Kazakh TV reporter giving way to gay Austrian fashion reporter Brüno Gehard. But maybe audiences had grown a tad tired of the crueller elements of Cohen’s brand of humour. Or maybe Borat was a highpoint that couldn’t be matched.

It all came to a dead stop with The Dictator, the fourth of Cohen’s big screen characters. As Hafez Aladeen, despotic ruler of the Republic of Wadiya, Cohen channelled an OTT version of General Gaddafi. But the combination of political commentary and scatological gags (whilst distantly echoing elements of 1970s Woody Allen) largely fell flat. Suddenly Cohen, like his transatlantic stablemate Mike Myers, risked losing all he had worked so hard to build.

Borat made an appearance on America’s Jimmy Kimmel chat show, busily promoting Grimsby and at the same time ridiculing Donald Trump. It’s where Cohen appears most happy – hiding behind his characters’ outrageousness and getting away with not-quite murder but not far from it.

Trump takes a beating in Grimsby, just as Daniel Radcliffe is the butt of a joke that skirts the boundaries of good taste. But then the entire film is built on a wobbly foundation of near-the-knuckle humour that has audiences equally choking on their popcorn and swallowing their tongues in shock.

Yet fans on both sides of the Atlantic seem to love him. He goes further than Myers and Stiller and dares to immerse himself in the type of crudity that Steve Coogan might seek to avoid. In that respect Cohen’s brand of comedy elevates him to an entirely different level.

It’s a form of unapologetically confrontational comedy that has brought him close to starting a riot, not least when as campy, fragrant Brüno he orchestrated a fight scene in front of 2,000 Arkansas rednecks. When Brüno kissed his boyfriend the affronted audience rained down metal chairs on the actors.

Will he ‘go Hollywood’ like so many other Brits? His track record thus far seems to suggest not. There have been guest spots in other comics’ work, not least a scene-stealing performance in Talladega Nights: The Ballad of Ricky Bobby in which he held his own against Will Ferrell. He also appeared in Anchorman 2, also with Ferrell, in what must represent one comic supporting another.

Tim Burton used him in Sweeney Todd, he was in Tom Hooper’s Les Misérables and popped up as a policeman in Martin Scorsese’s Hugo in an extended cameo that was reminiscent of Arthur (“Good moaning!”) Bostrom’s faux gendarme in TV’s ’Allo ’Allo.

But Hollywood appears to have been a misadventure. This anecdote is apparently typical of his experiences…

“I’ve spent a few years in Hollywood and it’s been a disaster, actually. Socialising has been very difficult for me. I went to a party the first week I was there and Jim Carrey was [present].

“He was complaining about being single and suddenly a quite attractive woman went past. She was looking at him so I said, ‘What about her? She looks like she’s up for it’. And he goes, ‘That’s my daughter…’ So mostly now I don’t go out in Hollywood!”

Grimsby (15) is out on general release.