Rambo still shooting from the lip

"What do you mean one of the most violent movies of all time?" he frothed. "It is the most violent movie of all time!"

Where the original Rambo film had just one death, the latest version has 236 killings at a rate of 2.59 a minute. Almost every brand of murder and mutilation is represented, with decapitation, disembowelling, torture, rape and drowning all featuring prominently. "When you're pushed, killing's as easy as breathing," drawls our husky hero.

A quarter of a century after the apocalyptic post-Vietnam movie First Blood hit our screens, Stallone's alter ego John Rambo is back.

For that, we can thank the Texan with whom America's action man shares his birth date, fellow pensioner George W Bush. The actor may not like the cut of Dubya's cloth – he is a confirmed McCain supporter – but the president's gung-ho antics in the Middle East have breathed life into a career that was in danger of disappearing with the Cold War.

"Maybe these movies wouldn't have been as interesting five years ago, but look what's happened in the world in that time; it's a whole different climate now," said Stallone. "After Vietnam there was a need for escapism. Rambo led to the birth of the real uber action film. I was part of that group with Arnold (Schwarzenegger] and Bruce (Willis] and there was a definite theme. It was about one-man armies."

In the collective consciousness, the dysfunctional Vietnam vet represented an America that wouldn't be pushed around. As Ronald Reagan memorably said before bombing Tripoli: "After seeing Rambo, I knew what to do in Libya."

This year's bloodbath of choice may be in Burma, where Rambo is forced to rescue a group of Christian missionaries, but America's impotence in the face of Al-Qaeda's jihad is the unmistakable backdrop.

Yet there is something unsettling about a man of Sly's advanced years taking up the cudgels on behalf of the free world. "There's no question about it, it's ludicrous," admits the 61-year-old. "It reeks of vanity and a lack of self-awareness, but I've been looking for the next Robert Mitchum or Steve McQueen and they just don't exist. Tough guys today are getting their hair done at Hollywood hairdressers. Whatever happened to having a beer and scratching your balls?"

Besides, Stallone is a baby-boomer, one of the Woodstock generation who grew up with the belief that life was theirs for the taking. He's not going to allow anyone to elbow him out of the limelight. "Society says: 'Step back, youth must be served.' I say: 'You're right, youth must be served – after us. Get in line. We're coming back for seconds and thirds, and when we're finished helping ourselves, it's your turn.' People say: 'Come on, grow old gracefully.' No, why? I'm not ready."

Stallone is a fighter in every sense, but then he's had to be. Born in the charity ward of a hospital in the New York ghetto of Hell's Kitchen, the doctor's forceps severed a nerve in his cheek, leaving him with his trademark droopy mouth. He came home to his mother Jackie, a chorus girl turned wrestler who gave him copies of Penthouse and Playboy as a 10-year-old to aid his reading, and his Italian father Frank, a hairdresser who regularly beat him with a leather polo whip until he bled.

"My childhood was terrible. I was not an attractive child," says Stallone. "I was sickly and had rickets and my personality was abhorrent to other children, so when growing up I enjoyed my own company and did a lot of fantasising."

Expelled from 14 schools for antisocial and violent behaviour, at 13 his desperate mother sent him to Devereaux Manor Hall in Pennsylvania, a last-chance boarding school for highly disturbed delinquents.

A loner, he craved respect but was so confrontational that he found it impossible to bond. He made no friends and was voted the pupil most likely to die in the electric chair. He still finds some friendships difficult. Despite being comfortable in male company – Gianni Versace was a close friend, as is Arnie Schwarzenegger, with whom he enjoys a drink most Saturdays – his disastrous love life includes two messy failed marriages costing him $35m and more models than Airfix.

Stallone's abusive father rammed home the message that "you weren't born with a brain so you'd better develop your body", turning him into a body-obsessed gym rat too self-absorbed to sustain a relationship.

"When you come from nothing and you are given everything – money, women, limos – it's crazy. It was all about me and my work and the excitement and the grandeur. Everything that detracted from me and my fame tended to suffer and wilt in the shade of my own glory."

He even dumped current wife Jennifer Flavin by FedEx letter when he thought he had got model Janice Dickinson pregnant. He eventually came back to Flavin, a rich woman in her own right, which is important to Stallone. When they tied the knot he asked the Pope if they could marry in the Sistine Chapel before settling for Blenheim Palace. Along with two sons from his first marriage, one of whom is autistic, he has three girls with Flavin, one of whom was born with a hole in her heart.

If Devereaux Manor Hall didn't gift him any friends, it did introduce him to the two passions in his life: boxing (for which he had a genuine talent) and acting. Those twin beacons of hope coalesced in 1975 when he saw Chuck 'The Bayonne Bleeder' Wepner knock down Muhammad Ali in Cleveland. He wrote Rocky in three days (and doesn't understand how Flaubert took 18 years to write Madame Bovary, "a lousy book and a lousy movie").

Producer Irwin Winkler wanted James Caan or Burt Reynolds as the lead rather than the unknown Stallone, but he held out. The rest is history: the film was made for a tenth of the standard budget in just 28 days and won the Oscar for best film in 1977, beating All the President's Men, Network and Taxi Driver. Stallone became only the third man after Charlie Chaplin and Orson Welles to be nominated for Academy Awards for best actor and best screenplay for the same film.

Even with expensive divorces and generous payments to his family, Stallone has never wanted for money and has a fortune estimated at $200m. He has become rich by investing his $20m per film wisely: he owns an $50m art collection including works by Bacon and Hockney, a fleet of vintage cars, more property than the Duke of Westminster, and he recently expanded his Planet Hollywood chain by opening a 250m hotel and casino in Las Vegas.

Yet money isn't everything, and Stallone is still that spiky teenager craving respect. In a moment of rare candour in 1997, he admitted 17 of his 30 films made him look stupid, adding: "I despise (my work over] the last 10 years".

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Stallone made his film debut with the lead in a 1970 hardcore porn film Party At Kitty And Stud's, and was paid $200 for the two-day shoot. Some sex scenes were edited out on later releases of the film designed to cash in on Stallone's fame.

Stallone's first proper acting role was as an uncredited subway thug in Woody Allen's Bananas in 1972.

In February 2007, Stallone was touring Australia to promote Rocky Balboa when he was fined 5,000 for taking 48 vials of the banned bodybuilding substance Jintropin, a human growth hormone, into the country.

Stallone says his next project will either be directing a film on Edgar Allan Poe from a script he developed as a penniless actor in the 1970s or a part in Inglorious Bastards, Quentin Tarantino's next film.

In July 2007, Stallone had a portrait of his wife Jennifer Flavin tattooed on his upper right arm by world-renowned tattoo artist Mike Devries.