There are certain risks involved in making a film about the filmmaking business. Too many in-jokes and you could alienate the punters, not enough parody and it looks self-indulgent.

Robert DeNiro’s latest film What Just Happened? boldly tries to negotiate those particular landmines as it fictionalises producer Art Linson’s memoirs.

You would think any film starring the Hollywood legend would be a shoo-in success, but in the cut-throat world of the movie industry, as the film shows, anything can happen.

Robert, however, in London to promote the film’s UK release, is quietly confident about its chances.

”I haven’t experienced [the brutality of the industry] first-hand yet, but the fact is, in Hollywood, if a movie isn’t well received, or doesn’t do well, even if it’s well received...

”With What Just Happened? Art and I have been getting calls from people who liked the movie very much and are complimentary. How it does, we don’t know, we hope it does well, because then it’s good.”

Robert plays Ben, a twice-divorced producer trying to juggle children, ex-wives, eccentric directors, stroppy actors and scared agents, all with his Bluetooth clamped to his ear.

”I think the film has a more European flavour, so it’s funny, but it also has all the other elements of sadness, drama and struggle,” says the 65-year-old.

”I think you’ll like Ben because he’s willing to put up with the struggle as much as whether he prevails.”

What Just Happened? came about after Robert read Art’s memoirs and offered to play him, as long as Art wrote the screenplay and co-produced the film.

”I read the book and laughed all the way through it and I said to Art, ‘You should write a screenplay and try and make a movie out of this and I would play the part’,” he explains.

But that’s as far as his involvement went, or so he says.

”It’s so hard to write a screenplay and Art was always complaining to me about that and the process that he goes through, so I thought it was best to leave him alone and give him as much support as I could.”

Barry Levinson, a previous collaborator of Robert’s, came on board to direct and the film was shot in just 33 days.

”There’s a certain energy and tautness when you’re working this fast, but it was OK,” says Robert.

”We did Wag The Dog in less time, I think that was 28 days, it was that way of doing it and that was it, but it was fun.

”We never shot scenes in just one take, but sometimes you’d have Barry moving around, so you had a scene going on and he’d arrive when someone was delivering a line,” he continues.

”Between me, Art and Barry, everybody knew this world from their perspective, we knew it would be funny to say the least and it was - and Art did such a good job and was so smart and funny about it.”

The plot revolves around Ben’s latest film, a ‘visionary’ drama starring Sean Penn, called Fiercely.

When it’s shown at a test screening, the audience are outraged by the ending, which lands Ben in a stand-off between the film’s rebellious, drug-taking director Jeremy (Michael Wincott) and the ball-breaking studio executive Lou (Catherine Keener).

Lou delivers an ultimatum: change the ending or the film will not go to the Cannes Film Festival.

Meanwhile, Ben is also confronted with a tubby, bearded and arrogant version of Bruce Willis, who refuses to shave for his role in Ben’s next production.

Bruce’s fictional agent Dick, played by John Torturro, is so afraid of his client that he suffers from paralysing stomach cramps.

In Art Linson’s memoirs, though, Bruce Willis was actually Alec Baldwin.

”I started with Alec,” jokes Robert.

”I said ‘I’ve got something to show you’ and then I thought, ‘nah, you don’t have a sense of humour’.”

Throughout his career, Robert insists he can’t remember ever being part of such a drama on a movie set.

”It was based on Art’s experience and we were lucky to get Bruce Willis for the role because he understood the joke, it was fun.”

In spite of his realistic potrayal of Ben, Robert counts himself as one of the lucky ones, who is not under as much pressure as the likes of Art Linson and other veteran producers to keep everything on track.

”I am in a better position, because when I’m acting in something, I don’t have problems, I don’t have the pressures.

”I have other pressures in what I’m doing as an actor, but the producing problems and directors’ problems, that very real pressure, scheduling, moment-to-moment decisions, that always at the end of the day boil down to money and the pressure from the money people to keep that cost down... Art’s used to it.

”I’ve been through it, but I like it when I don’t have that pressure.”

Robert DeNiro was born in New York City, the son of painters.

During the 60s, he acted in off-Broadway productions and had his first major screen role in Brian De Palma’s Greetings.

In 1973’s Mean Streets, he began his long-term collaboration with Oscar-winning director Martin Scorsese, who Robert affectionately calls Marty.

Together they have worked on eight films, including Taxi Driver (1976), which brought him international stardom due in part to the catchphrase ‘You talkin’ to me?’ and 1980’s Raging Bull for which Robert won his second Oscar.

The duo were rumoured to be teaming up again for the first time in 13 years, to make I Heard You Paint, based on a story about an Irish mob assassin.

”That’s something that Marty and I want to do very much,” he reveals.

”At this point the script is being written and we’ve got another even more ambitious plan of doing another movie connected to it in some way.”

In recent years, the actor has opted for more comedic roles and is known for his roles in Meet The Parents (2000) and Meet The Fockers (2004).

He has also turned his hand to directing, most recently 2006’s The Good Shepherd, starring Matt Damon and Angelina Jolie, and in 2002 he founded the TriBeCa Film Festival in New York to help lower Manhattan recover after 9/11.

Over the past year, Robert has also been very vocal in his support for Barack Obama - and now that he’s the President elect, he’s grateful.

”I couldn’t have imagined it any other way, it just would have been a disaster for our country and for the world if it had gone the other way, period. Thank God.”