What is the greatest year in cinema? There will never be a definitive answer. It’s all subjective of course, because it’s always a question of personal taste and opinion. But, for me, 1971 is indisputably the best ever in movie history. What stands out is the sheer variety of films on offer: what other year gives you Monty Python and Woody Allen, Spaghetti Westerns and Hammer Horror, the Carry On team and Ingmar Bergman?

Historically the year was important, too. It was all change in Hollywood, the end of the studio system. The studios still wielded enormous power, but they were like dinosaurs, out of date and out of time.

Some faced bankruptcy, others were bought out or forced to sell off their backlots to property developers. Box office attendances were down, too, and the old guard couldn’t gauge anymore what audiences wanted to see.

This led to the studio heads giving unprecedented freedom to younger writers and directors to make the kind of films they really wanted to make. This was really the start of what came to be dubbed the “New Hollywood”.

Influenced by the revolutionary new waves of cinema coming out of Europe, this generation of filmmakers gave us movies that were both innovative and morally ambiguous. Take Peter Bogdanovich’s The Last Picture Show, widely regarded as one of the seminal American films of the 70s.

It garnered eight Oscar nominations and helped launch a new generation of stars, notably Jeff Bridges, Cybill Shepherd and Ellen Burstyn. Newsweek acclaimed the film as, “The most impressive work by a young American director since Citizen Kane”.

Conversations about the greatest year in movies often revolve around 1939 and 1999.

Yes, those two years produced iconic pictures; the first including Gone with the Wind, Stagecoach and The Wizard of Oz; while the second turned out such films as The Blair Witch Project, Fight Club and The Matrix.

Yet 1971 also gave us Hal Ashby’s kooky Harold and Maude, Robert Altman’s revisionist western McCabe & Mrs Miller and Alan J Pakula’s superior thriller Klute. And what may be most striking about 1971 is just how many firsts there were.

George Lucas made his debut feature with THX 1138, a chilly dystopian vision of the future that is worlds away from Star Wars. Steven Spielberg made his feature debut, too, with Duel, about a monstrous truck terrorising a motorist. It aired as an ABC Movie of the Week in America and received a theatrical release in Europe.

Spielberg felt a strong emotional resonance to the material and the driver’s predicament – this feeling of being victimised – having been bullied as a kid at school for being Jewish. He has since said Duel was his life in the schoolyard. The truck was the bully and he was the car.

Other directors making their film debuts included Stephen Frears, with Gumshoe, and Mike Leigh with Bleak Moments. Monty Python made their first foray into cinema with their ‘greatest hits’ sketch film And Now For Something Completely Different.

Back on the other side of the Atlantic, actors Jack Nicholson and Clint Eastwood moved behind the camera for the first time. The latter’s directorial debut, Play Misty for Me, a thriller about a psychotic ex-girlfriend who stalks her former lover, hinted at his capabilities. Eastwood has subsequently directed more than 40 pictures. Nicholson’s time behind the camera, with Drive, He Said, was less successful.

It was a busy year for Eastwood in front of the camera, too, with The Beguiled and Dirty Harry both released in 1971. Playing San Francisco police detective Harry Callahan, the latter spawned a five-film franchise, and some of the most quotable movie lines in history: “Do you feel lucky, punk?” and “Go ahead, make my day.”

Harry’s on-screen arrival came just two months after the introduction of another infamous cop, Gene Hackman’s Jimmy ‘Popeye’ Doyle in The French Connection.

William Friedkin’s seminal police drama deservedly won the Oscar as the best film of 1971. Hackman also ended up with an Academy Award as best actor, although he had real problems with the darker aspects of the character, based on a real New York cop.

At one point he quit the production, only to be talked into returning by his agent.

In Melvin van Peebles’s landmark independent movie, Sweet Sweetback’s Baadasssss Song, the police are painted as a force of oppressive white supremacist power.

This film’s extraordinary success, combined with Gordon Parks’ Shaft, starring Richard Roundtree as a black private eye, initiated the Blaxploitation genre. There was a boom in martial arts pictures, too, in 1971, after the financial success of Bruce Lee’s first starring role in The Big Boss.

Films like Dirty Harry and the violent cinematic image of Bruce Lee caused consternation to many. By the late 60s and early 70s, filmmakers were no longer constrained by the shackles of censorship and were pushing the limits of sex and violence.

1971 was truly the year of savage cinema. Sam Peckinpah’s Straw Dogs, with its notorious rape scene, was called “The first American film that is a fascist work of art” by noted American critic Pauline Kael.

Ken Russell unleashed his possessed nuns in The Devils, and burnt poor old Oliver Reed at the stake, to boot. Stanley Kubrick brought Anthony Burgess’ urban parasites the Droogs to life in A Clockwork Orange. And Michael Caine’s London gangster was seen tearing up the criminal fraternity of Newcastle in Get Carter. Is it any wonder that by the end of the year the British censor announced his retirement?

1971 turned out to be a sparkling year for British pictures, the last for quite some time as the industry sank into financial recession and did not pick itself up again until the 1980s. We have not one, but six Hammer horror films, two Carry On comedies and the big screen outing for that most beloved of all television sitcoms Dad’s Army.

Nicolas Roeg made his first solo film as a director with the visually arresting Walkabout. John Schlesinger brought us the daring Sunday Bloody Sunday, while Joseph Losey’s period drama The Go-Between won the top prize at that year’s Cannes Film Festival.

Roman Polanski was up to his ankles in blood making his version of Shakespeare’s Macbeth on location in Wales, and falling behind schedule.

When the backers pulled out, Polanski’s friend Hugh Hefner flew over in his bunny jet and Playboy picked up the tab. Fortunately, the Playboy club in London was doing tremendous business and sacks of money kept coming down every week to pay the salaries of the crew.

Other European auteurs saw their films released in 1971, including Luchino Visconti’s Death in Venice, François Truffaut’s Les Deux Anglaises et le Continent, Pier Paolo Pasolini’s The Decameron, Louis Malle’s Murmur of the Heart, and a couple in the murder-mystery Giallo genre from Dario Argento.

Sergio Leone also made his final western, A Fistful of Dynamite, while there was an early work from the enfant terrible of German cinema, Rainer Werner Fassbinder, as well as the first English-language film from the master Ingmar Bergman.

Other highlights of the year include the film version of the musical Fiddler on the Roof. Music was a high point of Disney’s big release that year, the evergreen Bedknobs and Broomsticks. Sean Connery made his final appearance as James Bond in the official series with Diamonds Are Forever. And Jacques Tati bid farewell to his comic creation Mr Hulot.

And, bizarrely, there was a film financed by the Quaker company simply because they wanted to promote a new chocolate bar. Ironically the chocolate bar did not prove a success but the film, Willy Wonka and The Chocolate Factory, became a classic.

Rather like 1971 itself. In the 52 years since then, just like a fine wine, the year and the films it gave birth to, have improved with age.

• 1971: 100 Films from Cinema’s Greatest Year by Robert Sellers (History Press, £20) is published on August 31. To, pre-order, visit expressbookshop.com or call 020 3176 3832. Free UK P&P on orders over £25