An American in London

Betsy Blair recalls the moment Gene Kelly proposed to her. "It was in front of the Plaza Hotel in New York. We were sitting by the fountain and he said he couldn't leave me to the mercy of New York when he went to Hollywood. I said yes immediately. I didn't have any reservations at all. You don't when you're in love."

Blair had met Kelly two years earlier at an audition when she was 15. She had inadvertently turned up a day early and had spoken to a man moving tables and chairs. "I thought he was a busboy. I said, 'I'm here to see Mr Rose' and he asked me if I was a dancer. I said I was and he told me the audition was the following day. I fished the card out of my bag and sure enough it was, so I thanked this busboy and started to leave. Then he said, 'Are you a good dancer?' I turned round and said, 'Very.' The next day, I went to the audition and it was Gene moving the tables and chairs around. He was the choreographer."

Blair got the job and fell in love, spending the next two years working in nightclubs and on Broadway in musical comedies and in theatre. It was a big change for someone who had grown up in smalltown New Jersey. "I used to enter amateur shows, and being from the neighbourhood and being only nine, I won one. The prize was $20, which was a lot of money in the 30s. The man who ran the show spoke to my mother and it turned out it wasn't such an amateur show so I joined his troupe and I got paid $5 every Thursday. That was my first professional engagement. Then it all sort of happened."

Her second job was as a child photographic model. Then, with a schoolteacher mother and a father who sold insurance, Blair was set for university, winning a scholarship. But on the way back from a college interview - where she was told to come back the next year because she was too young - she saw an advertisement for dancers in a nightclub show. "I got off the train and said to my mother that I was going and I didn't care what Daddy said. So we convinced my father that because I was going to make $35 a week - more money than my brothers, who had been to university, were making - I would save and go to university the next year."

It was when that nightclub closed that Blair auditioned for another and met Kelly. "When I think about it now, that year and a half [in New York] was incredible but when you're young, nothing is surprising. You don't judge it, you don't think about it, it's just so much fun and so beautiful. I wasn't blasé about it - it was just what was happening."

After their honeymoon, Blair and Kelly arrived in Hollywood on December 7, 1941, the day the Japanese attacked Pearl Harbor. Contracted to David Selznick and unlikely to be drafted early, Kelly (who was 29) was yet to make a movie, so he sold war bonds while Blair volunteered in a hospital. However, it wasn't long before MGM asked him to be in For Me and My Gal and made a deal with Selznick to take over half of his contract. It was the birth of not just one of Hollywood's most talented stars, but of an icon too.

For Blair, however, Kelly was simply her husband. "I loved his work and he was a great dancer and he was also a really interesting, educated fellow. The fact that he was a star didn't matter to me. I was a snippy kid, I never thought of him as an icon."

Kelly made three movies before he went into the US Navy's photographic unit, a posting that frustrated him since, Blair says, he wanted to fight. Blair herself had moved from Hollywood back to New Jersey with their baby daughter, Kerry, understudying for the part of Laura in the first production of The Glass Menagerie on Broadway. Kelly was on the verge of being shipped to the Pacific when the atom bomb was dropped on Japan.

When the war finished, the family returned to the west coast. It was then that Kelly's career went meteoric, the high points of which included: Anchors Aweigh, for which he earned a best actor Oscar nomination; Ziegfeld Follies with Fred Astaire; The Pirate, in which he reprised his For Me and My Gal partnership with Judy Garland; On the Town; An American in Paris, for which he won a special Academy award; and Singin' in the Rain, which he acted in, co-directed and choreographed.

Throughout this was Blair. Didn't she feel that she was in his shadow? "Not at all. I did mean, sometime in the future, to be a serious actress but I had so much time. It didn't occur to me that this life would interfere, that I should be in New York if I wanted to be a serious actress." (This life included hosting legendary parties attended by the likes of Noel Coward, Garland and Frank Sinatra.)

Blair's life, which she calls "almost boring because it was so wonderful", changed when the Senate investigations subcommittee under the leadership of Joseph McCarthy started its witchhunts into "un-American activities". She and Kelly were both left-wing and even though she didn't suffer as much as others, she finds it hard to talk about now. "To be very left-wing in Hollywood was to work for the unions, to work for the blacks, the ordinary things that are social democratic principles. It was, if you were a writer, to try and write a film in which black people had a dignified position rather than just servants. At the time, you weren't to say you were a communist or you weren't a communist - they had no right to ask. I think now that the committee knew from the FBI who was a communist and who wasn't and they didn't call anyone who wasn't. I wasn't that important that I would have been called but it was an incomprehensible time."

In 1957, the year after she was nominated for a best actress Oscar for her role in Marty, Blair's marriage to Kelly ended, after which she moved to Paris. She will say nothing about their divorce other than, "I have nothing bad to say about Gene in any way. I can't, in a little interview, explain the complications of what I needed and what he needed. We were married 16 years and it just came to an end."

In Gene Kelly: Hollywood Greats - the accomplished and delightful biography of the star - Blair says she didn't want to be "an idolised little girl any more". Aside from that, she keeps her counsel.

In the five years she spent in France, Blair worked more than she had before or since, including appearing in Michelangelo Antonioni's Il Grido (The Cry). It was while filming at Pinewood that she met her second husband, Karel Reisz, who directed Saturday Night and Sunday Morning. They married in 1963.

Now in her late 70s and living in north London, Blair is still luminous. In a long velvet dress and drinking Diet Coke out of a silver tankard, she still has a sparkle in her eyes, at once dignified and mischievous. It may have been this that Stephen Daldry saw when he cast her in his new film, The Hours. "He called me up and asked me to have lunch. So I went thinking it must be Meryl Streep's mother and I can do that - we both come from New Jersey - but it wasn't. I play Julianne Moore's character in 50 years' time.

"You never stop wanting to act but I had forgotten how much I enjoyed it. I've often thought I was very lucky. To grow up in a small town is very lucky, to get all those real life values. Then I was in New York when you could still go walking in Central Park. And then to be in Hollywood and then Paris. Then to come and live here for the rest of my life. The timing of things has been very fortunate."

• Gene Kelly: Hollywood Greats is on BBC1 tonight at 10.35pm.