But I was also more sheltered and didn’t have that carefree or dangerous adolescent period.’ Does she regret that at all? Her talk to the genteel ladies of Beverly Hills centres around her newly published memoir, One From The Hart, and although two events precipitated the writing of the book – the death of her mother and her own lung cancer – it gave her a chance, she says, ‘to set the record straight about certain things’.Chief among them was the legacy of William Holden (the star of films such as Sabrina with Audrey Hepburn and The Bridge On The River Kwai) with whom she had a nine-year relationship.

When Powers was one day granted an audience at his summer residence in Italy, she was determined to speak Polish, as her mother was Polish-American. Born Stefania Zofya Federkiewicz in LA in 1942, she was sent to ballet classes with a young Natalie Wood and Jill St.

John – both of whom went on to marry Robert Wagner, ‘as I did too, on screen,’ says Powers. ‘There was a better atmosphere in the house after they divorced. ‘I never had any incidents, maybe because I wasn’t one of the beautiful girls – I was a tomboy.

When the series ended in 1984, she appeared in London’s West End, starring alongside Robert Wagner in Love Letters and in the 1991 musical Matador alongside a young John Barrowman.

It was in England three years ago, while she was in panto with Christopher Biggins, that the two events which led to her penning her memoir transpired.

At 68, she looks sleek and toned in a grey trouser suit, with her trademark red hair still retaining its lushness.

It’s a textbook display to any fledgling actress of the benefits of old-school Hollywood charm and deportment.

‘In one respect we were more adult in our comportment and in our behaviour,’ she says.

‘If you look at Mad Men, that’s a perfect example of how people looked and dressed. With a career spanning more than 50 years (including five years on the hugely popular TV series Hart To Hart with Robert Wagner) and a long-term relationship with the actor William Holden that sparked her commitment to wildlife conservation, Powers’ life certainly hasn’t lacked excitement.

It was a tragic end to an illustrious career, with accounts of Holden’s much-publicised battle with alcohol at times overshadowing his considerable achievements (including an Oscar for Stalag 17 and two further nominations).‘Writing the book gave me the perfect opportunity to clarify one of the most important relationships of my life – the one I had with Bill,’ says Powers. But it didn’t stop him achieving some extraordinary things.

'In the 1950s, environmentalism was almost unheard of, but Bill was at the vanguard of it early on.’They first met at a showbiz New Year’s Eve party in the late 1960s – ‘There I was, suddenly face to face with this glorious man whose work I admired and who was so self-effacing’ – and the couple started dating in 1972.

‘Because I’d started having CT scans regularly, I was very fortunate that it was spotted early.