In the temple of toys they're burning up. Outside the Zen Santas chill to their theme

"Look for the Zen Santas,'' says a voice on the end of a mobile phone. "Meet us outside Gap. We'll probably look a bit bizarre.'' But it's nearly Christmas and the streets of central London are busy with men in false beards and red suits. How will I be able to tell which ones are protesters who want me to resist globalisation and celebrate Buy Nothing Day? What exactly does a Zen Santa look like? "A bit like an ordinary Santa, really,'' admits the voice. "Only calmer.''

Calm is hard to find in Regent Street on the first weekend of December, at the start of the Christmas shopping season. The pavement is so crowded you can only shuffle forward a few steps at a time. Foolishly, I decide to kill time before Santa's arrival by joining the slow moving herds in Hamleys, the "finest toyshop in the world".

"Crikey,'' says Meryl from Birmingham, clutching her grandson's hand a little tighter as they enter a world of shiny surfaces, bright colours, floating balloons, and whirring mechanical devices. "Let's go to the top floor and work our way down.'' Everybody else is doing the same. "Keep moving, please,'' says a shop attendant with a walkie-talkie at the bottom of the elevator. "Keep moving faster.''

It is hard to believe but the store was even busier last year when consumers saw it as their patriotic duty to spend, and sales figures hit record highs. Simon Burke, chairman of Hamleys, has predicted slower sales this time. "We have had two very good Christmases in a row. This year will be solid but not spectacular.''

It will also be very hot. The temperature in the store rises with the escalator and the air becomes increasingly stuffy as the low purple ceiling closes in. Meryl is now carrying two coats, hats, scarves, gloves, and a couple of shopping bags in one hand while holding onto the boy with the other. We pass a blond girl in tears, distressed by the crowd. "Calm down, come on,'' says her dad, stroking her head. He has beads of sweat on his own brow.

"Here it is, darling,'' says a bearded grandfather, showing a remote control car to a boy in a Ford baseball cap. "What do you think of that?'' Not much, is the answer, to grandad's great dismay. The boy's eye has been caught instead by a hovercraft, twice the price at £100.

Once upon a time parents would brawl in the street for the last Buzz Lightyear, but now he sits in a darkened corner with Thunderbirds and Power Rangers, watching the little darlings go mad for this year's favourite super hero, Spider-Man. A plastic web-festooned Spiderbike will cost you £180.

Even the traditional options are no longer cheap. A dressing-up box for girls who want to be a nurse, a fairy and a princess, is nearly £40. One small tunnel for a wooden train set costs almost as much.

We all moan about such things every year and still buy them (although a survey last week showed that a quarter of all families have set a spending limit among themselves this year, and more than half of those have agreed to pay no more than £10 a present).

The real question is why anyone would want to come here on a Saturday and go through this crowded, over-heated endurance test. "I like the buzz of it actually,'' says Clive from Suffolk, who has come to town to buy for his nieces and nephews. He admits to lingering in the model aircraft section, remembering his childhood.

There is no such nostalgia for Ruth, a German woman visiting the store for the first time. "Did you go into the basement, where they're shooting things?'' The thunderous noise, flashing lights, and crowds at the entrance to the subterranean Cyberzone put me off, I confessed. "It was hell,'' she says. "I saw a woman have a breakdown in the queue to pay. She went very pale and suddenly started whimpering.''

We go in search of peace and Zen Santas. Michael Cronk and his friend Chris are sitting cross-legged in the centre of Carnaby Street, in full Father Christmas regalia. The tips of their fingers touch and their eyes are closed. David Beckham's face looks down on them from the Soccer Scene shop, as a young American girl they met on the way here holds up a banner that reads "Buy Less, Live More''. The shoppers, mostly tourists yet to hear that Carnaby Street stopped swinging 30 years ago, are utterly confused. "Are they supposed to be part of the Christmas decorations?'' wonders an Italian lady, posing for a snapshot behind the pair.

"They are the lot that are protesting outside the Chinese Embassy,'' a tall bald man confides to his companion, mistakenly. He refuses a leaflet that would put him right. "I'm not a protestor,'' protests Michael. "I see this as a holiday from spending, an enjoyable event.''

Buy Nothing Day is celebrated every year by the diverse anti-globalisation movement – not that it is really possible to tell how many people choose to stay in bed and spend nothing on principle rather than out of laziness. Michael, 22, has come up from Poole in Dorset. He bought his ticket in advance.

He wants us all to buy less, repair what we have, and exercise our spending power more responsibly by choosing recyclable, fairly traded goods, avoiding excessive packaging. The figures are persuasive: 20 per cent of the world's population is using up 80 per cent of its resources. But the trouble with protesting in the manic atmosphere of the West End in December is that sensory overload makes shoppers think they have seen everything before. Nothing is a surprise. "Oh look,'' says an elderly woman to her friend, as if rediscovering the Christmas lights or some other comforting sight. "There are the meditating Santas.''