is the word

Well of course they haven't as countless tv re-runs, a hugely successful video release and a popular stage show have ensured that generations growing up in the belief that the summer of 1978 counts as ancient history still know the words to 'Summer Lovin'' and the rest. For those involved in the film it has been a long 20 years. Newcomer John Travolta was a minor tv star who was about to score a huge hit with Saturday Night Fever when he was cast as Donny Zuko, leader of the T-Birds, the coolest gang in Rydell High School.

He was not the first choice for the role. Producer Allan Carr recalls that the studio wanted Henry Winkler - at the time scoring a big success on the small screen in Happy Days was their ideal, but when they relented on the male lead they demanded a star name a star name to play Danny's 'summer love', Sandy.

Carr was stuck, unable to find anyone who could sing, dance, was attractive and yet could play the vamp and the virgin within the same character. In the end a chance meeting at a dinner party with Olivia Newton-John made up his mind, and by the end of the evening he had offered her the role. But the English born, Australian raised singer was reluctant to take on the responsibility of a major feature film.

"I was a little nervous initially," she confirms. "I actually asked if I could do a screen test. After all I was 29 and would be playing a 17 year old so I wanted to make sure I could pull that off. Also I'd made a pretty bad musical several years before in England, and by 1977 my singing career was going really well and I didn't want to blow it. So I asked Allan if I could do a screen test, fortunately John agreed to do it with me, and thank goodness it worked."

The results of her efforts are there for all to see in their glory once again, and there is no denying that the chemistry between Newton-John and Travolta forms a major part of the film's enduring appeal. Much of what has been written recently has quoted the 49 year actress-singer admitting to nursing a major crush on her hunky co-star, which in turn seems so tame in these days of crude tabloid revelations and the bearing of souls so openly on any number of talk shows, that it is easy to forget the public perception of Olivia Newton-John in the '70s.

No-one watching the film was really surprised that this pert and pretty 29 year old could pass for 17, but they were a little more taken aback by the super-permed, lycra-clad, heavily made up sexpot that Sandy transforms herself into. This was not the Olivia Newton-John we knew and loved, the Queen mother of middle of the road music, the sweet innocent we could take home to mum and safely leave with dad. Whatever would Sir Cliff have said? Looking back now she admits that the film offered an unexpected break with that goody-goody image. "I think it paved it paved the way for me to do some of the raunchier stuff like 'Physical' later." she explains, "I never thought of any kind of goody-goody image though. It's not something I ever felt I had to live up to. I've never taken drugs and I never really drink, so there's nothing much there, but I am a normal person. Goody-two-shoes was Sandy and I'm me, so let's just separate the two."

Fair enough. But it is hard, on her many tv appearances in the last couple of weeks, to think of Olivia Newton-John as being so very - well - sweet. She seems to be the very epitome of wholesome loveliness, even if friend and Grease co-star Didi Conn (who played Frenchy) refers to her as being a 'hot mama' on occasion. Call me old fashioned, but that just makes her all the more appealing.

But there is, and always, more to Olivia Newton-John than glib descriptions and face values. A serious and highly talented singer, she has a new album coming out entitled 'Back With A Heart', featuring a new version of her previous hits 'I Honestly Love You'. She has also devoted much time to environmental causes, and was made Goodwill Ambassador by the UN. Most importantly she has given birth to a daughter, Chloe, who is now in her teens and a devoted Grease fan herself. All of which gives her the utmost satisfaction, reason to smile amidst all the hype and hullabaloo that surrounds the 20th anniversary of Grease. More poignantly, and another reason for a big smile, is her recovery from breast cancer that was first diagnosed in 1992. "As difficult thing as it was to go through I learned a lot out of it," she explains, "I'm stronger now. If you can go through anything like that it gives you strength, but I'm aware of how lucky I am to have survived it. You just have to cope with illness like that when it happens, there are millions of people coping with it all the time. Chloe is the most important thing in the world to me, and I had great doctors and a wonderful support system. You just do what you have to, but I'm very lucky, I'm six years clear and dry, and I feel very healthy and very strong." At the time her career was obviously put on hold and she remembers facing up to some tough decisions.

"For that first year, Chloe didn't know about the cancer," she continues. "I didn't even want the word mentioned in our house, as she'd lost her best friend to the disease a year before. So I didn't tell her about it. I just said I wasn't feeling well, and she was young enough to accept that.

"Then a year later I was back in Australia, and on the first day of school someone there told her about it. . She came running home and asked me why I hadn't told her, and I said I was healthy now and I didn't want to upset her, so thank goodness it took a year. She was kind of cross with me, but I think it was the right decision."

Not that she was particularly pro-faced about her ordeal, she even makes a joke when asked what she has been up to for the past 20 years. "I can't remember everything, in fact I can't remember a lot - that's one of the things about chemotherapy!"

The bright healthy smile and the sparkle in the eye tell you much about Olivia Newton John just as they may protect the private person beneath that thoroughly agreeable public image. Yet the one thing that seems certain in private and in public is that she is genuinely happy to be here, 20 years on, and enjoying her greatest movie moment in the company of her daughter.

"She loves Grease," Newton-John laughs, "sometimes when I'm out of town she'll put on the tape and go to sleep to it. But for me seeing the film all these years later has been a blast. And seeing everyone involved in it again has been incredible, because I never went to my own high school reunion. For me this was it.

"It was great fun and we all had a really good time, but it was deja vu in the weirdest way, and everyone kind of looked pretty much the same - which is always kind of a relief - so it was really great fun. And the first time we went to the premier 20 years ago we didn't know what anyone would think of the film. This time we knew they liked it, so we could sit back and enjoy it."

Words that could also apply to life for Olivia Newton-John now, as she looks ahead to the next 20 happy, healthy years.