My father, the painter

Bella Freud has been sitting for her father, Lucian, since she was 16 years old and fresh out of school. But he painted her well before that - in Baby on a Green Sofa, with her tiny arms outstretched and her fluttering eyelids heavy with sleep.

Strictly speaking, he painted her before that, too: she's the bump in Pregnant Girl, 1960-61 (the Girl, with head buried in that same green sofa, is Bernardine Coverley), a picture of striking sensuality, and perhaps, emotional confusion.

Forty-odd years later, Bella has her own baby, 16-month-old Jimmy, and her own business, designing sexy, formal-yet-seductive clothes for Jaeger and for her own label, which operates under a logo drawn by Lucian. Her father, meanwhile, has a major retrospective at Tate Britain, featuring 60 years of work. Most families have photo albums to remind them of the ways in which they've grown, the high points and low points, the lives shared. For the Freuds, there are also paintings.

"They're linked to times, good times and bad times, what we were all doing when they were painted," says Bella now, sitting in her creatively chaotic west London office-cum-studio, where racks of clothes jostle for attention against a wall covered in photographs of models, colourful cartoons, pages ripped from newspapers, stimuli of all kinds.

"I love all the pictures that I've sat for, and obviously they're the ones that I've got very special memories of. But I have a particular affection, too, for the ones dad has been working on at the same time as mine. The ones I've watched evolve." (Lucian Freud's modus operandi makes a distinction between "day" paintings and "night" paintings, with a four-hour break in between, so he's always working on at least two pictures at the same time.)

Bella Freud didn't grow up with her father. Her mother was 18 when she began an affair with the 40-ish Lucian, and their girls - Bella and Esther - were respectively six and four when Bernardine took them off on the hippie trail to Morocco. This was the "adventure" later fictionalised by Esther in the novel Hideous Kinky and turned into a film by Gillies MacKinnon, starring Kate Winslet as the kaftan-clad Julia, aka Bernardine.

Later, back in England, Bella was sent to a Rudolf Steiner school in Sussex, where children were encouraged to express themselves artistically rather than academically, a regime she loathed. Returning to London as soon as she could, Bella began at the now-historic Vivienne Westwood shop, Seditionaries, eventually launching her own design career after what sounds like a hedonistic few years spent partying in Rome.

The relationship between father and daughters now, however, is "very supportive" and clearly close. "He's an ally," says Bella simply. Sitting for her father - whom she refers to as both Lucian and dad - is an experience of paradoxical calmness and stimulation. Some critics have written of the apparent submissiveness of Freud's painted women, of their surrender to "unguarded passivity", but for Bella, the creative process, the posing of daughter for father, isn't like that at all.

"We talk a lot," she says. "He talks. He has an amazing memory for poetry and he has met people that I find very interesting, Picasso, Cocteau, and so on. I get many good ideas from him for my own work. But it's also a kind of standstill in time. No matter what's going on in my life, how overwrought I've been about things, I leave it all at the door to his studio. It doesn't work unless you dedicate yourself to it comworkpletely.

"In normal life there are so many ways for people to interfere or meddle or interrupt your time, but you know that, with Lucian, it's going to be quiet and undisturbed because that's how he's arranged it."