It might have been the way she slumped into her seat like an overgrown teenager, or the second time she said “dude”. Whenever it was, at some point I began to ask myself the same question that bitchy members of the London literati did two years ago: why on earth did Salman Rushdie marry her? She may be beautiful, have an arts degree from Clark, the American liberal college, and speak five languages (Hindi, Tamil, Italian, Spanish and English), but something about Padma Lakshmi makes it hard to take her seriously.

“So, dear,” The Sun once asked, “what first attracted you to the millionaire novelist Salman Rushdie?” Probably because of such remarks Lakshmi rarely grants interviews, but she is in London and keen to promote her British acting debut in ITV’s Sharpe’s Challenge — in which she happens to be very good.

It is also half-term for her stepson Milan, Rushdie’s eight-year-old from his third marriage. Despite her husband’s unhappy memories of the capital (years of living under a fatwa), the couple still spend about four months a year here. Usually they reside in Manhattan.

We meet in a members’ bar near her Notting Hill flat. She arrives late to a collective turning of heads. Looking bored in a vest and jeans, her beauty is still transcendent although her voice does rather spoil the effect. She is a nasal valley girl. She says she can’t win on being arm candy for the party-loving Rushdie. “Dude, sometimes I try to say I shouldn’t go to things with him but you know what, I’m f***** if I do and f***** if I don’t.”

That said, she is fun, albeit in an adolescent way. “I’m really happiest,” she opines, chewing, “when I’m playing rap music in my basement and doing something with my hands. I even bedazzled these jeans.” Meaning she attached rhinestones to them. “It took, like, 15 hours!” At this she collapses with giggles that make her seem, for all her 35 years, very childlike.

Although some might find it humorous to imagine the wife of a literary giant faffing about with her Levis while he writes another opus upstairs, Lakshmi does not seem vapid so much as young. “I’m very banal,” she says of her love for good food and beautiful clothes. “My husband is much more . . . complicated.

“There’s nothing useful about being married to him, though,” she continues. “I think it works against me.” Surely it must have benefits? “I do have it easy in that I can take business class instead of coach (economy), but I would have that if I was married to anybody.”

People forget, says Lakshmi, that she had a career before Tina Brown (who else?) introduced her to Rushdie at a New York party in the late 1990s. At 20 she was discovered as a model while in Spain (she worked for Vogue and Ralph Lauren, among others) before becoming a presenter on Italian television. In 1998 she wrote a cookbook about keeping a model’s figure on an exotic diet. It became an international bestseller.

These days she is writing her second cookbook, reading voraciously (Brillat-Savarin, Antonia Fraser) and looking for acting gigs: “I just want people to see me for my work and not just as somebody’s wife.”

She warms to her theme: “In fact, I’d have to be really dumb to think that being with a writer was going to help with an acting career. I live in America. They don’t give a shit about that stuff.”

She sighs: “I think that people make the mistake of thinking women are attracted to money and success, but what we’re really attracted to is men who’ve done something interesting.”

Born in Madras, Lakshmi’s parents divorced when she was two. Her mother, a nurse, moved to New York but her father, an executive with Pfizer, stayed put. Although she split her childhood between the two countries it was not a lavish upbringing, certainly not as lavish as her wedding, of which Jay McInerney, the American author, wrote, “It was one of those brilliantly lit New York moments, the kind of gathering we all dream of attending before we come here.”

The company she now keeps is similarly illustrious. “I met Cherie Blair last year at a small sitdown dinner,” she says, while chewing. “Yeah, she was, like . . . nice. Other than Cherie’s daughter I was the youngest one there by a couple of decades, which was fine. I’m used to that.”

Since she bridged the 23-year-age gap to marry Rushdie she is often the youngest at the table. She dines with the Knopflers, the Yentobs, the Kureishis, the Pinters. “Harold is so sexy on stage,” she says with a naughty smile.

It is easier to maintain this social life now security is “not an issue”. The fatwa, eased by the Iranian government in 1998, 10 years after The Satanic Verses was published, “is behind us. We live just as any other normal people live. We try to keep discreet but thank God it’s okay now. In New York we take the subway”. Does it still panic your husband? “You’d have to ask him.”

Rushdie’s only complaint, she thinks, is that he feels she is too preoccupied with her career: “Also we don’t have the same taste in music at all. He hates Kanye West and I love him.”

Does she subscribe to the Jerry Hall mantra for happy marriage — a cook in the kitchen, a whore in the bedroom? “I suggest people don’t take tips on marital bliss from Jerry Hall,” she sniffs.

Instead they share a love for food, a good book and Milan, whom she adores. “We have violent pillow fights. My husband gets really mad,” she laughs. “He’d be like, ‘Don’t wind him up before bed! Don’t shake him like that!’ It’s fun.” Does Rushdie sometimes feel as if he’s got two kids? “No,” she says, outraged. She plans to have her own in a year or two.

As she stands to leave and plants a kiss on my cheek, it occurs to me that her only real crime, apart from an addiction to youth, is being a good actress who married for love. “Well sure,” she agrees. “It’s not like I ran over a baby.”

Sharpe’s Challenge will begin on April 23 on ITV1