There's a photograph of Warren Beatty that I've often wondered about. In it, Nancy Reagan is beaming like a star-struck teenager. Warren Beatty is beside her. The occasion is a special White House screening of Reds, his formally daring 1981 biopic of John Reed, the American journalist who chronicled the Russian Revolution in the seminal book Ten Days That Shook the World.

Think about that. Reds. A major studio production, pre-glasnost, for which Beatty received the Academy Award for best director. And a box of cigars from fan-boy Fidel Castro. And, evidently, a warm reception from then US president Ronald Reagan. How on earth did he manage it?

"A 3½ hour movie about a communist who died," smiles Beatty, with an anti-pitch. "The last movie made with an intermission. I got it made because I had to. I came with a certain amount of commercial muscle. I had just made a movie called Heaven Can Wait. And it was a big hit. But it was still tough to get Reds going. Then again, it was tough to get Bulworth made. It's always tough. But I would not have been able to not make them. That had to happen. In one form or another."

Where to begin with Warren Beatty? At 80, he has spent six decades in the limelight, as a young heartthrob in Elia Kazan's Splendor in the Grass (1961), as a driving force behind the American New Wave that gave us Bonnie and Clyde (1967) and McCabe & Mrs Miller (1971). And he is also the award-winning writer, director, and producer of Heaven Can Wait (1978) and Bulworth (1998).

He has popped up in the writings of Hunter S Thompson, James Baldwin, Andy Warhol and Gore Vidal. He has popped up on the arm of (deep breath) Madonna, Barbra Streisand, Brigitte Bardot, Diane Keaton, Julie Christie, Joan Collins, Natalie Wood, Goldie Hawn and Elle Macpherson. A 2010 biography by Peter Biskind estimated that Beatty had slept with 12,775 women.

Beatty, rather understandably, is not a big fan of such unofficial biographies. “I’ve had – I think it’s 16 books – written about me,” he says. “I’ve read a few pages of most of them. I’ve never got past page 10. They are all baloney. But how do you sell a book? Let’s see what’s salacious and controversial. And then I see quotes taken from these books. But I’ve never co-operated with anyone who has written a book about me.”

Price of admission

He shrugs: “That’s the price of admission to fame, I think. And when you’ve been around for as long as I have, all the baloney adds up.”

There has been rather less Beatty-related baloney – "I think I deserve credit for not saying bullshit," he adds – since his marriage to Annette Bening in 1992. "I let so many years go by," he beams. "Not because I was afraid of marriage. But because I was afraid of divorce."

There currently seems little chance of that. Beatty and Bening have four children. He recites their ages, proudly: “Seventeen, 20, 22, 25. I’m very impressed by their integrity and by their ability to cope with things.”

Headlines (and baloney) would have us believe that Beatty's domesticity has coincided with a withdrawal from public life. He hasn't given interviews in many years. He hasn't appeared in a movie since Town & Country in 2001, nor directed one since Bulworth in 1998. He laughs at the idea that he's the new Garbo.

He was of course back in the spotlight recently at the Oscars. He has already stated that he is done talking about the envelope mix-up that led to the actor and Faye Dunaway announcing La La Land as Best Picture winner, when the real winner was Moonlight. (Any subsequent inquiries into the matter have, as per a recent episode of the Graham Norton Show, been politely batted away by Beatty, who dismisses the incident as "chaotic".)

When we meet, he's London on the promotional trail for Rules Don't Apply, the first film he has written, directed and starred in almost two decades. Smart, well-preserved and witty, he has lost none of the charm he used in that Nancy Reagan photo. There are one-liners that I suspect are tried-and-tested standards (opening gambit: "We have to stop meeting like this") and off-the-cuff quips that would make any stand-up comedian proud.

When I tell him that, many Oscars and movies into his career, my mum still refers to him as “Shirley MacLaine’s brother”, he roars with laughter and snaps back: “I know someone thinks the same thing: Shirley MacLaine.”

Reclusive billionaire

Rules Don't Apply concerns an aspiring actress (Lily Collins, daughter of Phil Collins) and an ambitious chauffeur (Alden Ehrenreich, the new Han Solo), two youngsters hailing from America's Bible Belt, who arrive in Hollywood during the late-1950s. Their employer is the reclusive billionaire Howard Hughes (played by Beatty).

"I never knew him," says Beatty. "But I would hear the stories about him – and everybody had stories about him – and they would make me laugh. Because the things he did to make himself seem mysterious were ridiculous. I would say the same thing about Greta Garbo. But ridiculous worked. Because it did keep me interested in Greta Garbo and it kept me interested in Howard Hughes."

Hughes has long fascinated Hollywood, first as a producer and then as the enigmatic subject of such varied projects as The Amazing Howard Hughes, Melvin and Howard and The Aviator. But Rules Don't Apply, as Beatty notes, is not strictly speaking, a biopic.

"I would say that the movie – thematically and primarily – is about the consequences of that thing that has so often made Americans the laughing stock of Europe: American Protestant sexual puritanism."

There are shades of the autobiographical here. Henry Warren Beaty – as it reads on his birth certificate – was born and raised in a Baptist family in Virginia. A lifelong movie fan, he accompanied his sister Shirley to theatres and later followed her to Hollywood.

“Let’s say I got the joke about puritanism just after I left the Bible Belt,” he says. “I arrived in Hollywood in 1958, the same year [the characters] did.”

Is the film, in some sense, concerned with the religious fundamentalism underpinning the current American administration? “You don’t think the current president is a puritan, do you?” he says laughing. “I think we are maybe looking at a last gasp. But I don’t want to make the mistake of going into political stuff here. Once you start me on politics, you’ll be sorry that you did.”

Beatty for president

Norman Mailer once lamented: "If only Warren Beatty had been president." It's not such a far-fetched idea. In the early 1970s, Beatty vigorously campaigned for George McGovern; in the 1980s, he was a prominent supporter of Gary Hart's two bids for the Democratic presidential nomination.

"I go back to Bobby Kennedy. I'm a liberal Democrat. But I've been very friendly with some conservatives. I was friendly with Ronald Reagan. We would have a jocular argument every time we got together. John McCain is a good friend of mine. I don't agree with him on some very important things, but there are things we do agree on. One in particular is campaign finance reform. There's nobody better than John McCain on that issue."

He pauses: “See? I told you not to let me start about politics.”

The first star of Hollywood's countercultural cinema was fortunate to arrive at a moment when the old studio system was disintegrating. "I was lucky enough to get in to the business during the era of Cahiers du Cinema, Godard, Truffaut, Renais in France; Visconti, Fellini, Pontecorvo in Italy; Woodfall Films, Tony Richardson, John Schlesinger, Karel Reisz over here; George Stevens, Willie Wyler, Billy Wilder, Freddie Zimmerman, David Lean, and the new guy was Stanley Kubrick in Hollywood. And then came the moment when the inmates took over the asylum."

That moment was precipitated by Bonnie and Clyde, a film that would never have happened, says Beatty, "if the studios hadn't loosened their grip and stopped looking constantly in the rear view mirror".

Beatty remains hopeful that new platforms will once again create more interesting, adult-friendly cinema, as an alternative to contemporary cinema’s homogeneity. “We live in an era of sequels and tent poles and water slides and theme parks. The audience knows exactly what it is going to get before they have left the house.

Gutenberg press

“Movies used to be two hours long because they were originally financed by theatre owners. But now all bets are off. Nobody says that a book has to be 120 pages long. It can be any number of pages. And we can own it or rent it. And put it down on our bedside table and pick it up again when we’re ready. So that’s where we are headed.”

He reaches into his back pocket and produces a phone: “This is the Gutenberg press now. Nobody ever said: Gee, I don’t have enough money to write a book. And now you can shoot a movie on your phone. So rather than sit around and mourn the demise of the big screen and an audience of hundreds, we should be waiting for a revival of movies that are not sequels: a revival of the unknown. That can’t come soon enough.”

Where did all go wrong? He's too polite to name names, although we suspect he's pointing the finger at Breakout, a B-movie starring Charles Bronson, which, in 1975 was released on hundreds of screens and advertised in 42 prime-time TV spots. Previously, Hollywood studios did not advertise on network television, where advertising was prohibitively expensive.

"I won't name the movie because that would be unfair. It was also financed by someone I know. But the movie was very, very bad. Everybody says Jaws was the first wide release. But the first was something else. It had 30 seconds in it that was exciting.

"And the person that put up half the money for production went to the studio. The studio was ready for bankruptcy. And the person said: 'I want 600 theatres, or you'll never get any money from me again.' And then he got television spots. And he got all of his money back in two weeks. It's like the invention of penicillin. It's a story of unintended effects. Because at that point Lew Wasserman, who had taken over at Universal, saw this and thought: Well, I've got a good movie. I've got Jaws. So I'm going to put that in 700 theatres. And that became the new way of distributing movies. Everybody had to get the joke on Friday night.

“So now we’re in 5,000 or 6,000 theatres across the US with a simultaneous release all over the world. That’s unfortunate. It’s like what’s happening with the news: sensation takes precedent over truth and gravity.”

Rules Don't Apply is on general release

BEATTY ON ‘BONNIE AND CLYDE’

Warren Beatty produced, cast, and starred in Bonnie and Clyde in 1967. It would change his career, and, indeed, cinema. But not right away. The New York Times's Bosley Crowther dismissed the picture as "a cheap piece of bald-faced slapstick". Pauline Kael responded to the brickbats, initially, as a lone American voice in the wilderness: "How do you make a good movie in this country without being jumped on?"

"I started putting Bonnie and Clyde together in 1964," recalls Beatty. "It was not like anything that had been done before. So it got a very mixed response when it opened in the States. Many people were outraged by the mix of comedy and violence. The New York Times panned it; Time magazine panned the hell out of it; Newsweek panned it. And these were the important publications. With important critics.

"Then the movie opened in England and the praise for it was unanimous. Within weeks, the New York Times got rid of the original critic. Then Time magazine – within three months of having panned it – put the movie on the cover and said it had changed movie making. Newsweek magazine withdrew their pan and wrote a rave. That was Joe Morgenstern who now writes for the Wall Street Journal. A good critic."