“When I’m in the UK I can’t resist Maltesers and Twiglets - the evil combination. Luckily, I live in the US so can’t get them easily, which is probably a good thing,” she says.
The actress confesses that she can have as many as “three or four” in one sitting - three or four what? Packets? Boxes? Those hulking great tubes you get at Christmas? Alas, no. She means three or four actual sweets.
Not even a mouthful, really. Particularly when you think they are mostly made of air.
“Three or four Maltesers, that’s always enough,” she claims. So there you have it.
I am here, in a Dublin hotel, meeting Jane because, at 61, she’s been all over the papers recently looking half her age.
How does she do it? Obviously having the raw material to have been a Bond Girl helps, but there must be more to it.
I have 90 minutes with her, but I seem to have discovered her “secret” in two: her brain considers five Maltesers a binge. Such a brain would never allow a body or face to sag.
But she doesn’t just owe it to iron-will in the face of chocolate: her body, including those incredible toned arms - I bet she has never even heard the words “bingo wings” let alone suffered from them - are the result of hours pounding away at the gym and Pilates classes.
“I’m not obsessive but I do work at it,” admits Jane, who’s in a fitted red sleeveless dress that would make most women her age shudder.
In the flesh, she is stunning, with the sort of waist most of us wave goodbye to around the age of ten.
And when she places her tiny hands round her middle, they almost meet. Hard to believe this waist once measured 56 inches.
Granted she was pregnant with twins at the time, but it’s a bit like hearing she once had three heads.
“It was nearly impossible, physically,” she admits. “I looked like Tweedledum. I have very small feet, too, so I actually toppled over once or twice and had to be caught.”
That was 17 years ago. She already had two children by the time she fell pregnant with twins Johnny and Kris (named after her friends Johnny Cash and Christopher Reeve, apparently).
Now she has two grandchildren “and another on the way”, and is on her fourth marriage. Yet in the flesh she’s not only annoyingly svelte, but truly beautiful. All the more so because she has - surprisingly, given the prevalence of Botox - proper wrinkles.
Her forehead creases like an accordion when her eyebrows move, and there are definite lines under her eyes. “I’m proud of my wrinkles,” she says. “They give my face character. As an actress, you mess with that at your peril.”
It would be rude to rummage behind her ears for signs of surgery, so we will have to take her word that there have been “no facelifts, nothing like that”. She has tried Botox, but wasn’t impressed.
“I think the good thing about my face is it has always been expressive. With Botox that goes - not what you want as an actress.”
Not that she’s a complete surgery refusenik . . .
She’s had her eyes done: “Top and bottom, years ago. I was asked by photographers if I’d consider getting them done because they spent so much time touching up pictures. It wasn’t a big deal. I went out for lunch the day after surgery.”
The only other time she went under the knife was for a boob job, she says. “It was 20 years ago. I’d breastfed my first two children and things weren’t what they had been.
“I’d never had a big bust - I always say they had to make smaller implants just for me, but I wanted the shape back. Clothes fit and look better. It was a good move.”
Would she consider a full facelift?
“I’ll never say never, but I’ve just filmed a part where I play a grandmother. You need character in your face for that.”
She scrolls through her phone for pictures of her grey wig. She looks magnificent and I say she should let herself go grey. Seymour looks horrified. “I’m not grey. Well, I have a bit at the sides, but overall I’m not really. And my mother had no grey when she died aged 92.”
Jane has been quite earnest till now, but leans forward and grins. “Well, she said she had no grey hair, but actually she was entirely grey.”
Her hair has always been her crowning glory, and no, she won’t be cutting it any time soon. “People say women shouldn’t have long hair over a certain age, but I’ve never done what everyone says.”
Most actresses get a bit shirty if you want to spent an entire interview talking about how they look.
But Seymour accepts that her looks and her career have always been intrinsically linked.
She was over here to fulfil promotional contracts (she’s the face of the CC clothing range), and attended a screening of Skyfall, the latest Bond movie. As a former Bond Girl herself - Solitaire in Live And Let Die, almost 40 years ago - the film brought back memories.
“I was very innocent when I got the part. I was 20. I’d been in The Onedin Line but a Bond movie - it wasn’t something I aspired to. I was hoping to do a good BBC drama, maybe some theatre. Next thing I knew I was in a Bond film.
“When I watch it, all I think is ‘they certainly didn’t give me the job on my acting ability’ - because the acting was terrible!
“I’m under no illusions, I only got the job because of how I looked.
“The irony was that they told me they’d found the perfect girl to play Solitaire - then proceeded to change everything about me. I had to dye my hair black and they tried to make me wear contact lenses.”
Even today her eyes are mesmerising, and unusual, as they are different colours. One brown; one green. “I have contact lenses so I can have just one colour if the part requires it, but I don’t look like me if my eyes are the one colour. I look more... original like this.”
She has a toughness and practicality that belies her graceful exterior. Her real name is Joyce and her hobbies are the sort you expect grannies called Joyce to have.
Conversation lurches from her love of sewing, knitting and embroidery to how she once “fell into Roger Moore’s private parts”. Asked for her favourite Bond, unsurprisingly she says: “It is Roger because he was my Bond, but Pierce Brosnan is a neighbour and I play golf at the same club as Sean Connery”.
Her private life reads like a movie script. Husband number one was Michael Attenborough, son of Richard. They married in 1971 but it was over in two years. Marriage number two, to businessman Geoffrey Planer, in 1977, was even shorter.
But it was her 1981 marriage to businessman David Flynn that brought her, she says, “to the edge”. They had two children - Katherine, now 30, and Sean, 27 - but divorced in 1992 amid accusations of his alcoholism and affairs.
She came out of it financially ruined and says: “I was never bankrupt. I was afraid it could happen, but it didn’t. I called my agent and said ‘I need to work yesterday’ and he called all the different companies and said ‘Jane will do anything.’ “
Anything turned out to be Dr Quinn Medicine Woman, a show not expected to do well, which turned into a TV juggernaut. It won her a Golden Globe - and her life back.
She was filming Dr Quinn when she had IVF to have her twin sons with her fourth husband, movie director James Keach. Two attempts had ended in miscarriages and her sons were premature: “But we got our happy ending, which was all that matters,” she says.
So what do her now teenage boys make of the fact that their mom was a Bond Girl? She laughs.
“I show them a picture of me at the same age as their girlfriends and say ‘that was Mom’ - but at home, I’m not glamorous. I’m just... Mom.” - Daily Mail