In the unlikely setting of Selfridges yesterday, 600 people stripped off in the name of art. They were posing for a shoot by the controversial photographer Spencer Tunick, who has made his name depicting masses of the human body, au naturel.

He found himself overwhelmed with volunteers eager to shed their clothing - and their inhibitions. The first models began arriving at 6am. By 8.30am the 750-strong queue stretched round the block. There were so many some had to be turned away.

Linda Budden, a 50-year-old personal assistant from Lingfield, Surrey, was persuaded into participating by her student daughter Gemma, 20. 'I'm always saying I need to get out more,' said Mrs Budden.

On the train up from Guildford, the pair met teacher Bonny Holland, 44, who decided to strip because her husband and 15-year-old son told her she wouldn't dare.

'I don't have a lot of excitement in my life, so I thought it would be fun,' she said. 'My son just thinks I'm sad.'

Here, one of the participants, Oliver Bennett, from the Daily Mail, describes what it was like to be a nude model for a day.

As the rest of the country breakfasted, walked dogs and worshipped, I spent yesterday morning lying naked with hundreds of strangers on the floor of a London department store.

I was on the latest shoot by Spencer Tunick, launching Selfridges' BodyCraze promotion, devoted to the growing interest in body modification and adornment.

By 7.30am there was a queue of about 200 people outside the store - rather like the first day of the sales, except the only prize was a signed snap of the event.

They were a youngish and quite fashionable crowd. In front of me were a couple of punk-ish young women; behind me a man and a woman who both worked at Selfridges and were here for a laugh.

Most were under 35, I'd say. I estimated there were slightly more men than women.

I started chatting to my fellow streakers. There was a young mother, Georgina, who'd had an anxiety dream about stripping off the night before. 'I almost didn't come after that,' she said.

Her partner, a teacher, had stayed at home. 'He decided that if any of the kids at school saw him in the papers, his life wouldn't be worth living.'

Her friend, an Australian actress called Tash, professed to an exhibitionist streak. 'I love taking my clothes off,' she gushed. 'Any opportunity, I'm afraid.'

Then I saw someone I knew. She came over. 'Tell you what,' she whispered. 'I won't look at you, if you don't look at me.'

We all signed a disclaimer-cum-model release form, filed into the store and were given a plastic bag each for our clothes.

Stewards ushered us towards the perfume department, where we were instructed to sit down, still clothed for the time being. Ah, the last moments of self-respect.

As I chatted to people it became clear there were some exhibitionists and nude activists. Perhaps there was the odd pervert. But most people seemed to be into the art, or along for a bit of fun.

tension was rising but Tunick finally arrived. A swarthy 36-year-old with a pleasant manner (useful if your work is asking masses of people to take off their clothes) he thanked us and took us through an introductory spiel.

'Remember to remove all jewellery, but you can hang on to your glasses.' Who was going to remove their specs just before the clothes came off, anyway?

Then it was that time: the moment of deshabille. I shuffled out of my jeans and jacket, putting them into the bag, and looked up.

Around me, bras and pants were being divested, and the temperature rose by a couple of degrees. I caught one woman's eye and found my feet had suddenly become fascinating.

Now we were undressed, and the gallery of flesh was astonishing. Tattoos and piercings, sometimes on the unlikeliest of bodies, were revealed.

One woman in her thirties had a mastectomy. There was one glamorous individual clearly between genders: female below, male above.

I'm not the most worked-out body in the world, but there were far wobblier frames than mine in evidence - yet in this context, it really didn't seem to matter. Tunick started directing, keeping his light touch but with an additional bit of Hitchcockian steel.

'Anyone with tan lines go to the back! Move right back into perfume,' he bellowed. 'As far as Catherine Zeta-Jones!' It was only her picture, unfortunately.

We lay down to Tunick's instruction, with a lot of shufflings and 'excuse-mes' and as little body contact as possible.

One couple were wrapped up in each other's arms - would they mimic the couple who had initiated, ahem, intimate relations on a Tunick shoot? Thankfully, no.

Tunick's emollient-but-firm tones came over that speaker: 'Sit down, don't look at the camera, now lie down, don't cross your legs.' Click.

He asked us to stand up and look intently at the perfume stands - naked browsing - then we turned like a shoal of mackerel and walked over to the escalators (I worried slightly about other people's verrucas at this point).

'Get on the escalators, three to a step,' ordered Tunick. In a few minutes, there was a river of pink flesh up three flights of escalators.

It was all going swimmingly, then the second escalator started up without warning.

There were a few yelps of panic, and a block of people fell backwards-Someone had turned the start button on - accident, or foul play? - but it was quickly turned off. A naked tragedy had been averted.

For the final part of this shoot, we had to lean our heads on the person-in front, in order to make a human chain.

I'd been jockeying for a good position behind a nice Spanish girl. But as Tunick had said during his demonstration, 'Some of you will be lucky. Others won't.' In the event, my forehead came to rest on the open-pored back of a middleaged gentleman. Yuck.

The shoot was almost over. 'I want my clothes back on,' whined a goose-pimpled female.

But first, the girls had to have a photograph taken in the lingerie section.

The last job was for us to make an egg shape by bending over, and after that it was time to regain our dignity, which I decided was a bit like going to an anti- strip club, where the opposite to sexy disrobing occurred.

Then it was a wrap, and I rejoined my friend, who had strayed away from the pack and been confronted by a leering cleaner.

'I suddenly felt really vulnerable,' she confided. 'The freedom has suddenly evaporated.'

We retrieved our clothes and I heard one woman say: 'Did that really happen?' - a lot of participants likened it to being in a dream.

Then, it was all over. I had been Tunicked.