I first clapped eyes on Emilia Fox about six years ago in Habitat on Kensington High Street. “Oh look, a celebrity,” I thought, and began stalking her through the aisles, overcome by a bizarre desire to watch an ingénue shop for budget crockery, when I was distracted by her strange appearance. It was a baking hot day, yet Fox had swaddled her tiny frame in several scarves, like some half-dead Egyptian mummy. She looked wan, fragile and — she won’t like me saying this — rather baleful. I met her properly last summer and, though she looked healthier, the melancholic vibe remained. She was chatty but remote. Everything was “marvellous” or “delicious”, but the eyes were glazed.

Not any more. On a rainy Tuesday afternoon, Fox positively swaggers into Electric House in Notting Hill, eyes a-twinkle and thankfully wearing only one scarf. “Hallo!”she cries and gives me a bear hug. I’m aghast. I’d expected to find an emotional wreck. It is only a few weeks since she filed for divorce from her husband of three and a half years, the actor Jared Harris. Yet she has never looked so self-assured. She’s just done this shoot for Style, shrugging off her English-rose profile for that of full-on sex kitten. What’s up?

Granted, her career is ticking over nicely. Fox spends the majority of the year filming Silent Witness, then slots in prestige films, such as this summer’s Dorian Gray. She is a muse for Temperley, Armani and even Roberto Cavalli, who all send her pretty things to wear. She has a bijou house in west London and, of course, there’s a grand theatrical dynasty propping her up (her parents are Edward Fox and Joanna David, then there’s uncle James, cousin Laurence . . . I could go on).

She looks fantastic: Fox isn’t wearing a stitch of make-up today and looks about 24. Not bad when you consider she’s actually 34, currently working nights and has spent the past year watching her marriage fall apart.

It’s not often one genuinely cares about the divorce olympics of the Hello! set (such as Fox’s broken-off engagement to Vic Reeves in the early Noughties), but I did feel a twinge of sadness when I heard she’d split from Harris. For one thing, they’d laid out their recipe for successful love in one of those painfully optimistic “how we met” interviews in a Sunday supplement (sample quote: “when you meet the right person in life, then you just know, don’t you?”). Then there was the day Harris proposed, filling her house from top to bottom with her favourite wild flowers, so she awoke as if in an indoor meadow, descending a floral staircase to find her man waiting in the garden with a ring. There followed a wedding ceremony in Dorset in 2005, where the thespian clans of Fox and Harris (Jared is Richard Harris’s son) were yoked together under a specially released cloud of rare-breed butterflies, and the happy couple departed in a horse and trap in a cloud of confetti. They made a pact that they would never spend more than two weeks apart, no matter where in the world they were.

But by 2008, the reality of working on different continents was too much to bear. Harris lived in the couple’s house in Los Angeles, while Emilia stayed in London, where she was getting more work. “Trying to create two lives is complicated,” she says. “Jared is the most amazing man, and you certainly don’t stop loving someone who has been in your life like that, but it’s a horrible cliché that we were away from each other for so long when I realised last summer we’d seen each other only three times in a year.” So it isn’t the case, as a friend of yours told a tabloid, that he was too glum for you? “These ‘friends’ are imaginary,” she sighs. “It couldn’t be further from the truth. He’s the first person to make life fun for everyone, always with a story to tell — something he got from his dad, actually, who was a wonderful life force.”

She pauses. “We’d also been through a really emotional thing the year before. I had a miscarriage, and we didn’t find time to deal with that.” She says this quietly, without drama, expecting no sympathy. “You just get on with it and go, ‘Well, it’s great, because at least my system’s working.’ ” Had you been trying for a baby, I ask. “No, we hadn’t at all.” Was he with you when it happened? “Yes, he was, thank heavens. Lots of people go through it and don’t talk about it, but I would recommend that if it happens to you, you have to talk about it.” But you didn’t? “I bottled it. Well, we bottled it between us. Although you think physically you’ve got over it, you have to deal with it emotionally — and I don’t think we did that. You get swept along by life and work.”

And you weren’t even really living together? “Well, quite,” she says flatly. Didn’t your mother once say that if one half of a couple wasn’t willing to sacrifice their career, then home life would be “chaos”? “Yes. I think it does become chaos within your relationship. But then, on the other hand, you can’t give up your career and then feel furious 20 years later. We should have been able to support each other in a relationship and gone to work because, like everyone, we have to pay the mortgage. It’s strange, being in this position now.” Because you feel like you’ve failed? “Well, we were both equally responsible for our relationship. It just didn’t sustain itself. What can you do?”

It’s odd how the shock of it has made her much surer of herself. Gone is the wispy floatiness of yore and — odder still — the melancholy. She speaks evenly, breaking into frequent peals of laughter, and is resolutely unluvvie. She says she has been seeing a psychoanalyst, something she had tried in the past, but “I never thought I had enough to talk about”.

Admittedly, it seems there wasn’t much to vex her in her early life. She played the cello, went to Francis Holland and Bryanston schools, read obsessively and eventually went to Oxford to read English. Entering the family firm was no picnic. Her parents warned her off it and her paternal grandmother was even fiercer. “She said ‘someone’ had told her I’d never be an actress because I’d need to change my hair, my face, my teeth. I was heartbroken, devastated. She said ‘someone’ who was close within our family had said it to her. She could be wicked, though, so I’m pretty sure it was just her.” Fox stuck with it, but she reckons her famous folks didn’t help. “It’s why people love The X Factor — it’s the fairy tale of the underdog rising to stardom. Absolutely nobody wants another flipping child of an actor to do well.”

It was while shooting Randall and Hopkirk (Deceased) in 2000 that she met Reeves and embarked on her kooky six-month fling. “A blur,” is how she recalls it now, with a blush. Was it here she developed a penchant for older men? He was 15 years her senior, Harris 13, and other boyfriends have been a decade older. She met Harris in 2003, during an ill-fated West End production of Les Liaisons Dangereuses that received such stinking reviews it came off after three weeks. At the time, she joked you were more likely to catch the clap than the show, but said it was the best job she’d ever done because “meeting Jared on that play is the best thing that has happened to me in my life”.

“I remember thinking early on how incredibly happy I was,” she says now. “It permeated my life. Wonderful jobs, wonderful friends. But when I got to the point where I was unhappy, it had a ripple effect again.” She cocks her head in thought. “Essentially I’m a sunny person. I wake up every morning and think the world is a good place. It’s very hard being a sunny person when you’re not feeling happy . . . but I’m getting there.” I’m wondering what the secret is — divorce? Therapy? Getting older? — when she hits it on the head. “Put simply, after all this, I care less about what people think of me these days. I think that’s the trick.”

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