IT HAS been more than three decades since Olivia Newton-John last toured the UK and it’s a very different woman who returns to these shores.

“I can barely remember that tour,” she laughs on the phone from California. “It was a crazy time.”

In 1978, Olivia was a 29-year-old singer and former Eurovision entrant who had just starred opposite John Travolta in Grease – the film of the Broadway musical that saw the actress don those famous spandex trousers.

The film had made her a star almost overnight and set the scene for a decade of album covers featuring Olivia in leather. These days, the Grease trousers have been mothballed at the back of her wardrobe – “I’m trying to age gracefully!”– and her focus has shifted to rather weightier personal projects.

The friendship forged with Travolta remains; last year they recorded a Christmas album together after Olivia texted him to say their Grease duet You’re The One That I Want, had become the best-selling duet in pop history.

Olivia Newton-John is 64 now, a twice-married mother of 28-year-old Chloe, and has battled breast cancer and faced the loss of her partner who disappeared on a fishing trip.

Travolta, 59, has also been through a lot, including the death of his son, Jett.

Although they don’t see each other often, good friends can just pick up where they left off, says Olivia. She still thinks fondly of Grease and is breezy about the fact she continues to be asked about it so long after the event.

“I feel very lucky to have been in a movie that was so beloved by so many people. Not many actors get that chance.”

It took her some time to be able to watch it without squirming though.

“I can enjoy it now. I feel more detached from it.”

It helped that her second husband of four years, businessman John Easterling, had never seen the film. He spent years living in the Amazon (he runs natural health firm Amazon Herb Company) and “it wasn’t part of his world. I loved that about him. But it was nice to rediscover the movie with him.”

The couple married in 2008 in a secret mountaintop ceremony in Peru.

Olivia divorced her first husband, Chloe’s father Matt Lattanzi, after he had an affair just a year after she lost her father, was diagnosed with breast cancer and was forced to cancel the tour intended to herald her comeback.

Later, Patrick McDermott, her boyfriend of nine years, disappeared on a fishing trip. His body has never been found.

The singer had therapy and a brief period on antidepressants to help her through but now says she tries to rely on the power of positive thinking.

“I think it’s incredibly important. It’s much easier to go to doom and gloom in hard times and to be positive takes effort and focus but it makes for a happier life. My diagnosis was 20 years ago and I’m very fortunate to be healthy and in the best place I’ve ever been.”

She made a number of ‘healing albums’ and opened the Olivia Newton John Cancer and Wellness Centre in Melbourne, Australia, where patients can try art therapy, music and massage to help them through their illness. Although she spends a lot of time working out and is conscious of what she eats, her illness has made her glad – rather than afraid – of ageing.

She says: “I’m grateful for every year because the alternative is that you’re not here.”

There’s been some debate about whether or not the star has had plastic surgery but she claims it’s nothing more than genetics and careful eating.

“My mum looked great into her 80s so I hope I can maintain my looks, too. I take tons of herbs and products my husband created, work out, play tennis, get outside in nature and think happy, positive thoughts. There’s nothing more ageing than worry!”

Born in Cambridge to a Welsh mother and German father, Olivia’s maternal grandfather was Nobel Prize-winning atomic physicist Max Born (one of her nicknames is Olivia Neutron Bomb), and her father Bryn was an MI5 officer.

She was six when her family emigrated to Melbourne. Although she dropped out of high school in her mid-teens and returned to live in London, she says she thinks of herself primarily as an Aussie. In 1975, she moved to the US where she had become well known as a pop star. She has had more than 25 Top 40 singles. It’s a delight to be touring again, she says, and to be returning to the UK happier and more healthy than she’s ever been.

“I think we change and grow so much over the years. I was a young woman when I last came to tour the UK. Now I’m a grown-up person…hopefully!”