DAME Joan Collins knows how to turn heads.

The private section of the art-deco restaurant at London’s five-star hotel Claridge’s is one of her favourite spots (and is naturally reserved for very VIPs), so she knows exactly where to go for our post-shoot interview.

But as the glamorous actress gracefully sashays her way through the packed dining room, she doesn’t appear to notice the effect she has on her fellow diners.

She leaves them open-mouthed and in no doubt that, yes, she really does look that good in the flesh. The octogenarian is clear, though, that her age-defying appearance is natural.

“If people want to think I’ve had surgery, then…” she shrugs.

“You can tell [I haven’t] because I have lines and jowls. When I see women around my age I think: ‘Oh, really? My gosh, I look quite a bit…’ I think I look pretty good!”

She sure does. Her bouffant hair is immaculately coiffed and her face doesn’t show any telltale signs of being touched by a surgeon’s scalpel, even though she could easily pass for someone 25 years younger.

Famously, Joan is a huge advocate of keeping her skin out of the sun.

“Also not putting on weight – it’s fatal. I have this [she grabs her lower stomach] and can’t get rid of it. It doesn’t matter what I do. I have a trainer who comes over and I do stretches and lunges. We don’t do anything too strenuous because I don’t believe in ‘no pain no gain’.”

Dame Joan – who insists we call her Joan minutes into our chat – has been defying expectations since she made her stage debut in 1942 aged nine – despite her own father, talent agent Joseph Collins, warning she’d be “washed-up” by 23.

“That was the thinking in the ‘50s,” she laughs.

“When I was 21 I was put under contract at 20th Century Fox for seven years, because 27 or 28 was considered to be the cut-off time for the beauty and youth of girls.”

Fortunately, Joan proved both her dad and the male studio bosses wrong and secured her star status by appearing in 70 films to date, as well as featuring in a host of high-profile TV shows including Star Trek and Will & Grace.

But during her time in the industry the star has also faced uphill battles, from escaping predatory film-makers and being pressured into taking weight-loss pills to fighting for equal pay.

However, the challenges have only made her more determined, and standing by her strong views has paid off. At an age when most actresses have long been forgotten, she is a star even bigger than the shoulder pads sported by her most iconic character, society super-bitch Alexis Colby on American soap opera Dynasty.

“I’m in a business where it’s survive or die, and I went through the jungle alone. I didn’t have a mentor or the world’s greatest agent looking after me,” she says matter-of-factly

“There are older-women parts, but quite frankly they’re going to go first of all to Judi Dench, Maggie Smith, Helen Mirren, Meryl Streep or Susan Sarandon. There are 20 women they’re going to go through before they get to me.”

That certainly wasn’t the case when she appeared in Thelma & Louise-style rom-com The Time of Their Lives out on DVD this month, after director Roger Goldby wrote it with Joan in mind.

Billed as a “feel-good OAP romp”, Joan plays faded Hollywood sex siren Helen, who is desperate to reclaim the spotlight.

“It’s got a great honesty about it. Fame is totally fleeting, and that’s one of the things I learned very early on. It casts a light on the misery of celebs as they get older. At fan conventions you see people you haven’t heard of for 30 or 40 years selling their photographs. You’re like: ‘That’s so and so, they were so beautiful,’ and now they’re absolutely unknown. They love the fame, and unfortunately it’s gone.”

Joan is well aware that she has broken the usual actress trajectory and knows how pitifully rare this kind of movie is – the three main stars have a combined age of 235

“Today, big-budget films are made by big businesses, and all of the companies have one motive in mind – to make money,” she explains.

“Their audience is mostly young men between the ages of 12 and 28 and they want to see young, nubile girls.

“I know quite a few young actresses in LA and work out with a couple of them in the gym. I say: ‘You’re so thin and you’re 25. What are you doing?’ This particular actress who is very well-known said: ‘I have to look thin. That’s what the directors want when I audition.’ If you’re over 71/2st or 8st, forget it, you’re considered fat.”

It’s one of the reasons why Joan advised her god-daughter, model Cara Delevingne, 24, not to become an actress, as she knows the pressures of losing weight as a young woman in Hollywood. She recounts an experience she had in her 20s when she weighed 9st and was told to lose 8lb.

“I was sent to a studio doctor as they thought I was too fat. He gave me these little green pills to take every morning, which I did, but then I couldn’t sleep at night so he gave me sleeping pills.

“I had a boyfriend at the time who was married – it’s the only time I’ve had a married boyfriend and it’s a misery, so I don’t advise anybody to do it – and he said: ‘What are you doing?’

“I told him that I took the pills and it was fabulous because I hardly ever ate and lost half a stone. He said: ‘These are [ADHD and narcolepsy drug] Dexedrine and are poison.’ He threw them down the loo and said not to ever take them again.

“I did some research and found out they’re what destroyed Judy Garland. So many in my profession have been destroyed by drugs, and it’s the rare actor who doesn’t get consumed by them.”

Fortunately Joan is a rarity. She swore off drugs after she says she was once forced to take cocaine at a party during the late ‘60s.

But having successfully swerved the pressure to fit the Hollywood mould, the beautiful young actress soon found herself being preyed on by the powerful men of the movie world.

“It started off being a fight at 17 – producers, directors, actors and heads of studios all wanting to take a piece of you, if you know what I mean. It was very predatory, and so many were like that. After talking to other young actresses at the time, we just accepted that’s the way men were.

“It was nothing for a man to pinch your bottom or push your hair back and say: ‘You’re such a cute little thing.’ You grinned and bore it and pushed it to the back of your mind. It even happened at school – a pastor put his hand on my thigh and stroked it. But you didn’t think ‘dirty old man’ and report him to your mother. That’s what they were like. Sorry men!”

Joan is relieved that female empowerment means that times have changed, but she does question whether it has come at a cost to men.

“I think we’ve lost men being gallant – opening doors, carrying our parcels, helping put our bags into the plane’s overhead lockers. I think there’s been over-militancy with some women and it’s turned men off. But I don’t want to get hate mail, so let’s move on.”

Moving swiftly on is the attitude that Joan has successfully employed for her entire career. As she grew older she refused to ever be forced into submission again and instead became a trailblazer.

At a time when it wasn’t wholly accepted for women to speak out, Joan fought Dynasty bosses to make Alexis (who she based on Donald Trump) fashionable, swapping tame tweed suits and blouses for flamboyant Yves Saint Laurent gowns.

Before Joan, the show’s ratings were unimpressive, but when she joined for the second series in 1981, everything changed. By 1985 Dynasty was the No.1 show in America and had won five Golden Globes.

It’s not hard to see why Alexis’ ultra-glam frocks and catfights with rival Krystle Carrington (played by Linda Evans) – including that spat in the lily pond – became the stuff of small-screen legend and made millions tune in for the seven years it ran.

But on learning that her co-star John Forsythe, who played on-screen ex-husband Blake Carrington, was being paid around £8,000 more an episode, she went to bosses and demanded she too should earn £39,000.

“I was told: ‘You’ve got ideas above your station and we’re not going to have you back.’ So I said fine and went off to Paris. I wasn’t in the first episode of season three because I was holding out for more money because I felt I deserved it.

“People say: ‘Why did you do Playboy?’ [Joan posed topless aged 50 in 1983] and I say: ‘Because I got paid for the first time ever!’ I was on the cover of every other magazine and you don’t get paid for that.”

Joan swiftly returned to Dynasty after having her pay increased to match her co-star’s. But did making her opinions heard ever cause problems?

“Yes, I got a lot of flack and hate mail. [People thought playing Alexis] was what I was really like, which of course it isn’t.”

Like Alexis, Joan has also developed a reputation – unfairly – as a maneater. She’s been married five times, most enduringly to Percy Gibson and the couple recently celebrated their 15th anniversary.

“I have a great husband and am so lucky. My god, you know in Hollywood this is a record? No one has been married for 15 years!” she laughs.

They met when theatre producer Percy worked on Joan’s Love Letters tour in 2000, and began a relationship 10 months later. Inevitably eyebrows were raised about their 32-year age gap.

“What’s interesting is both our fathers were born within three years of each other. We have very similar outlooks, even though he’s younger than me. There’s a stigma, but very rarely do the press mention it now. It doesn’t bother us at all. He’s always had a mature look, so if you see pictures of us together it doesn’t look like there’s this huge age difference.”

Talking about her beloved Percy is when Joan is at her most relaxed, and it’s clear that she’s besotted. What’s more, we’re in the hotel where they tied the knot in 2002.

“I love his sense of humour. He’s incredibly kind, nice and caring. It doesn’t mean that we don’t bicker and argue. And he smokes! But I’m not going to stop him. Other than that, we’re very happy. We talked about the fact when we got together, you know: ‘Do you want to have kids?’ He didn’t, which is great. He’s not a huge fan of children.”

Joan has two children – Tara and Alexander from her second marriage to actor and singer Antony Newley, and a third, Katyana from her third marriage to American businessman Ron Kass. Their marriage broke down after Joan discovered her husband’s drug problem, which he’d spent most of Joan’s earnings on.

“He lost his job, so suddenly I was the breadwinner. At one point I was carting around three children under the age of 12. But you know, that which does not kill you makes you stronger, and I’ve never let anything get me down. I’ve never suffered from depression. Well, I did the other day for about half a day,” she laughs.

“It’s this movie I’m supposed to be doing. We were ready to shoot and then the money fell out. I felt anger, depression, sadness: ‘I’ll never work again.’ But I got into bed, ate some chocolate and watched a movie.”

It’s a remarkable statement considering Joan’s personal history. Her fourth marriage to Swedish singer Peter Holm in 1985 ended after two years due to his adultery, but it was her first marriage to Maxwell Reed that had the most impact on her.

At 17 she was drugged and raped by the Irish actor, then went on to marry him in 1952 due to feelings of guilt and not having the courage to report it. He later tried to sell Joan for £10,000 to an Arab sheik, leading to Joan filing for divorce in 1956.

While in September 2015, her dear younger sister Jackie – a pioneer of the bonkbuster novel – died from breast cancer aged 77 after battling it for six years. She only told Joan she was ill two weeks before her death.

“She was so brave,” she says softly.

“We were very close. She loved Percy, and Percy adored her. It took me a long time to get over it. But what can you do? That’s life, and we’re all going to go, darling. When you’ve got to go, you’ve got to go. It made me aware that time runs out for everyone, so make every day count.”

As she gets ready to leave, she fields a call to sort a dress for an awards ceremony, discusses plans for a new movie and gives a parting hug (a rarity, according to her team) before meeting her daughter to go shopping.

No one could deny that Joan is living life to the full.

The Time of Their Lives is out on digital download July 17 & DVD July 31.