A lot of people get confused when they see this image. They think it was done by computer, but we actually took pigment powder, mixed it with talc to get the right ice-cream pastel colours, and brushed it into the cats.

The owners were two proud members of the Persian cat club. I can't remember how I found them, but they turned up in a van, covered in cat fur, and stood breathing down my neck as I took the picture. We were worried about putting all that powder into the animals' fur, but they said: "Oh no, they absolutely love it." The cats were such vain creatures - they adored being touched and pampered.

We didn't really think about which cats, or how many, should be done in which colours. We just did each one, and then they had to go back into their cat beds in the owners' van. I think I lost count of how many were pink and how many were blue, but when we were finished they all came out and looked great together. There wasn't enough light to do the picture indoors - but, by a fluke, all the cats seemed to gravitate to this clematis at the bottom of some steps. I didn't arrange them. This is just what the cats did, and they all pretty much stayed where they were throughout. So it's actually quite a naturalistic portrait - apart from the colour.

At the time, in May 1998, I had no idea how the picture would resonate with people. But it has been the image I've been asked about the most. For some reason, people are just fascinated with it - more than any model, house or celebrity I've ever shot. Everyone wants to know about the pastel cats.

Interview by Leo Benedictus

Curriculum vitae

Born: Guildofrd, 1970

Studied: Exeter Art College

Inspirations: Cecil Beaton, Irving Penn, Will McBride

Low point: Every time it pours with rain

High point: When it rains and you realise you can shoot everything inside. There was a camping series we did in Devon. It poured for the whole week, so we set the tents up in a library inside a house.

Pet hate: People who take it all too seriously. It kills the magic.

Dream subject: I'd love to do Geraldine Chaplin. I love the way she looks, and of course, there's the Charlie Chaplin connection.

· Pictures, an exhibition of Tim Walker photographs, is at the Design Museum, London SE1, until September 7.