Interview: Vidal Sassoon

"I don't sort of sit in a chair and pompously feel proud of myself about all the things we might have accomplished," he continues. "The essence is, what can we do next? And will it be good? It was always looking forwards, never backwards."

Indeed, how else can you explain the extraordinary rise of someone whose earliest years were spent in poverty, as his mother, Betty, struggled to raise him and his younger brother, Ivor, after being abandoned by their father?

When he was five she took the difficult step of handing Sassoon to the Spanish and Portugese Jewish Orphanage in Lauderdale Road, Maida Vale. He spent seven years there, but unlike Ivor, who had joined him a year-and-a-half later and who died when he was 46, Sassoon says he came to terms with the experience early on.

"I argued with Ivor about this. He said: 'Why did we have to go to an orphange?', and I said: 'Because Mother had nothing, and she was being evicted'. Ivor was a wonderful guy but he had problems about being in the orphanage. I can't say I did."

It was the first house he lived in that had a bathroom with hot water. Before that he had been in tenements with outside toilets and kitchens with cold water. "If you live that kind of life, you never forget it," he says. "Or you shouldn't even try to forget it. And I think it affects you politically. It has me, for sure."

When he was 14, Betty had a "premonition" that he would become a hairdresser and dragged Sassoon to Adolph Cohen, in Whitechapel, who, to the boy's dismay, waived his usual fee and took him on as an apprentice for free. "So I was shampooing at 14," he sighs. "But I've always thought that had I the opportunity for an education, I would have been an architect. There's no question about it."

A few years later he was leading a double life, washing hair and secretly fighting fascists with the 43 Group, alongside tough ex servicemen such as the war hero Gerry Flamberg ("250 pounds of muscle", he says). Sassoon had experienced antisemitic taunts as a schoolboy, but it was the Holocaust that showed him where these could lead. When Oswald Mosley and his Blackshirts regrouped after the war, "there was no question: you had to be one of the 43 Group. I was just one of the young guys that tried to help," he says modestly, "but the fascist party was smashed in the streets - without the help of the police, unfortunately."

Dachau, Auschwitz, Belsen and the rest had instilled a Zionist zeal in Betty and many others, and when Israel was formed in1948, Sassoon eagerly joined the Palmach – the elite fighting force of the Haganah paramilitary - to help defend the fledgling state. He wanted to - and did - see action: "I wasn't going over there to sit in an office . . . I thought if we don't fight for a piece of land and make it work, then the whole Holocaust thing was a terrible waste. But this way at least we got a country out of it."

Sassoon might have stayed in Israel but for a telegram from Betty, who had remarried, saying his stepfather had suffered a heart attack, and they needed him to earn money. Hairdressing was all he knew, and reluctantly he returned to the profession that he'd always felt ambivalent towards. "I loved the fact that there was lots of pretty girls coming in and out; I didn't love hair. When I came back, though, I decided to give it my all." Israel had changed him, he says. "The sense of what we'd done gave me an enormous confidence, and I really felt as if I belonged. And, funnily enough, it gave me a feeling of belonging in London, too. Or belonging anywhere: this is our world, that kind of thing."

That confidence would help him to begin revolutionising hairdressing when he opened his first salon on Bond Street in 1954. He envisaged a new kind of styling that moved away from the backcombing, teasing and lacquering to which women's hair had been subjected, and that would be based on architecture. Whereas building design had moved on in exciting ways, hair was stuck in the past. "It had been done beautifully, it all looked very pretty, but we had to get the cut right so that it swung into position, and stayed there," he says.

The cuts became geometric, using bone structure as the underlying foundation. And in Sassoon's brave new world of styling, they lasted and were easy to manage. "A working woman could save a few shillings a week, and then every five weeks she'd come in and we'd cut her hair," he says. "She could shampoo it under the shower, swing it and dry it off or just let it dry by itself. It changed the lives of many young girls who'd never had the opportunity to be styled like that before."

It took 10 years to get the geometric cuts to work efficiently, he says. "But by 1964 half the people were walking around London swinging their heads and the hair would just fall back where we cut it."

Caught up in the creative melting-pot of Sixties London, Sassoon worked like a man possessed. He was "crazy", says one of his former colleagues in the documentary. "He's right," Sassoon laughs.

He could be "pretty strict at times," he admits. "But if you were a hairdresser 50 years ago, people thought you'd either crawled down from the wall or you couldn't get a job in another field. So we had to raise the standard of the way people thought about us as well as raise the standard of how we acted as hairdressers."

Sassoon collaborated on iconic looks with fashion designer Mary Quant, cut actress Nancy Kwan's long black tresses into a geometric bob that took him global when it was photographed by Terence Donovan and published in Vogue, earned $5000 for cutting Mia Farrow's hair for the film Rosemary's Baby in a boxing ring in Hollywood, sensationally created the Five Point geometric cut - "the ultimate in hairdressing as far as I'm concerned" – and went on to start (and then sell) his own hair-product line.

His salon reflected the creative and egalitarian spirit of the '60s. Socialites, actors and working girls happily rubbed shoulders, while he says be benefited from the exchange of ideas that was happening in London at the time between people from different cultures and different creative pursuits. "Suddenly there was just this wonderful meritocracy of people from all walks of life," he says.

Despite the number of movie stars who passed through his doors, or were in his circle of friends, the only times he was ever star-struck were when he met architects. "I had been working on film people for so long, that if they were truly nice, no problem, we were nice in return. But if you got someone that's a bit snotty, we didn't need them. Truly, we didn't. But I got on with most of them fine. Albert Finney was lovely."

As the interview comes to an end, we return briefly to Israel and whether the country today is the one he envisaged in 1948. Sassoon says they had no illusions at the time that "many in the Arab world would be anti-Israel and would like to push you into the sea . . . Now we have a million and a quarter Arabs living in Israel, with all democratic rights. That's really good." On the other hand, Fatah's recent deal with Hamas was "very unforgiving" and has "put peace back", he believes.

Reflecting on himself as a Jew, he says, "in the final analysis, because of all the things I have been through, I feel very humble, in a way, that we produced so many incredible people, and there's only 13 million of us in the world, and we still keep producing.

"Essentially, I just have a certain pride in the tribe."

'Vidal Sassoon The Movie: How One Man Changed the World with a Pair of Scissors' is out on May 20. 'Vidal: The Autobiography' is published by Macmillan