Helena Christensen has a fetish for antiques — and as one of the original supermodels she is a cherished collector’s item herself. So she opened an antiques shop in New York and bought a car more redolent of Miss Marple than a former Miss Denmark. “I ride a lavender blue 1970 Morris Minor, the only type of car I have ever had,” she says merrily. Boy, she must cut a dash on the Upper East Side.

Nor is this her first flirtation with ancient British tin. It follows a green Morris Minor, which even in top gear could be overtaken by grannies pulling wicker baskets. The Morris Minor Owners Club, not renowned for its supermodel members, should make her patron.

Odd though it may seem, the car is very Helena: whatever oomph it might lack, many see in its curvaceous lines one of the prettiest automotive designs of all. In recent years bohemians have been snapping them up and Helena is decidedly boho. While other models fritter their days fretting about split ends or snorting cocaine in limos, the great Dane, 36, is reinventing herself as a photographer, actress and DJ. She was in London recently for a show of her own snaps, An Eye for Beauty.

Christensen is also a single mother after splitting from her actor boyfriend Norman Reedus three years ago, leaving her with son Mingus. She avoids nannies and spends afternoons with her son. “The key,” she laughs in perfect, sexily accented English, “is to turn it into a game.” Mingus, 5, has started school in New York, but she takes him on snapping assignments and he accompanies Christensen to Copenhagen and her chaotic 17th century loft apartment where her Peruvian mother Elsa stops Mingus jumping in the canal.

“He is turning into a little human being, with all the good stuff and the bad,” says Christensen. “I don’t think I can ever settle down. My life has been one of travel and moving on, but I have to be more stable with my little man. I am sure when he is grown I will pass him a joint and he will say, ‘Mother, what are you wearing?’” It is a relief to hear her laugh. I had anticipated a finger-wagging rebuke. Last time I interviewed her I did not take quite seriously enough her campaign to save the orang-utan. Her letter of complaint, one of the most trenchant this newspaper has ever received, ran to several f-words.

She has been single since Reedus and claims men never chat her up. Who would dare? “Some days are bleaker than others,” she says. “You know it is going to change eventually, so just indulge the melancholy. There are depressions. But you just have to think, ‘Thank God everyone you love is healthy’.”

Christensen is that rare beast, a beauty with brain, so catwalk fripperies were never going to satisfy her. Her old rivals can’t get out of bed for less than £10,000; sometimes she can’t get out of bed for depression. “I can’t think about the future. I always take the past with me; you can train that, somehow. Someday we are going to die and I don’t want to think about it. Why aren’t people freaked out by it?” It is hard to fathom why she is a model. She was mad about archeology but was waylaid when voted Miss Denmark aged 18 and went on to become a defining face of the age. “When I was offered a modelling job it seemed a little shallow but I am glad,” she smiles. “I said, ‘F***, I’ll do it’.” Far from being a 24-hour party, she makes it sound hellish: “It got really lonely. I wasn’t the normal 18-year-old. I was leading this eccentric life, staying in a five-star hotel in Hong Kong, yet I could not afford to phone home. And I would only be there for 17 hours. There would be no time to visit shops or museums. I saw the world but didn’t really see it.”

Still, it beats stacking shelves in Bognor. She laughs: “It’s definitely superficial, but it’s a great form of superficial.” And lucrative — she is said to have £14m in her piggy bank.

“I have saved as I have my child to think about. And I am definitely into materialism. I am no idiot. I recognise a model is a mannequin to sell things, and the money gives you options later.” After sounding world-weary about modelling she says: “You are displaying great art on your body. It is not just getting up in front of a camera and putting a hand on your waist.”

You might imagine being feted as a sexpot would produce a Naomi Campbell ego. No so. “You get used to rejection: my picture might have been sent to 100 people a day and 50 could have rejected me.” That has happened? “Of course. There are thousands of models.”

Reports of her retiring are exaggerated: “I have just shot a Dom Perignon campaign for Karl Lagerfeld.” But snapping young models makes her realise she is of a different generation. Their mistakes must infuriate her. “Of course,” she says. “I have to learn patience. But I wasn’t able to do cool stuff aged 18. And I am amazed how many are 17 going on 40. They are so focused.”

She concedes she wins photographic commissions because of her celebrity, but does not care. “I am not naive; I am not going to turn down work.”

With those coldly beautiful eyes she could be forbidding, but one warms to Helena. Despite her gloom she says: “I have been so damn lucky. It has been worth the ride.” Even if the chosen ride of this major model is a Morris Minor.

On her car radio

She likes to hear the Smiths, featuring Morrissey, a band she has loved since her gloomy adolescence, but also likes club music and has become a DJ: “It is one way of listening to what you like!”