I stand on a stool and prepare to clean acres of dusty blue tiles. Meanwhile, second-hand chiller cabinets are being wheeled into place, sturdy men heave in cardboard boxes of Special K from a van outside, and a beef farmer from Devon turns up with a box full of mince. My partner in grime, university lecturer Nuala O'Sullivan, busily scrubs a wooden window-frame.
"There's years of dirt in here, years!" gasps O'Sullivan, who lectures on business psychology at the University of Westminster. What's the psychology of volunteering to work in a supermarket, I wonder. "Routine and ritual," she replies. "That's what you get from religion. It's the same with volunteering. "
Arthur Potts Dawson, the mastermind behind The People's Supermarket, is certainly full of what one might loosely define as organic missionary zeal. A tall, youthful and reasonably optimistic chap who set up the London eco-restaurant Acorn House, (and is vaguely related to Mick Jagger, inter alia), Potts Dawson hopes that once his baby takes off, the likes of Tesco and Asda will be as a bad dream. We will all put in our community service and revel in 1970s-style food bills, while the big boys founder.
This is because in return for washing walls at TPS, you will be eligible for a 10 per cent shopping discount, and the ability to buy about 20 special "People's" foodstuffs at artificially low prices. Ordinary shoppers will be able to use the store, but not access the cheaper prices. Only we cleaners qualify for that.
"We'll have the People's Milk, and the People's Loaf. A beautiful big loaf of freshly baked bread! £1.85 to ordinary shoppers. £1 to members!," says Potts Dawson, who signs group emails with a personal, Citizen Smith-style mantra "To the Power of All".
While we are talking, his mother wafts in. A vision in sequinned cheesecloth and open-toed sandals, Mrs Potts Dawson has arrived from Somerset to inspect what her socialist-minded son is up to. Arthur takes us on a tour of the shop, formerly a decrepit local store and before that, an ancient branch of The Enemy (Tesco).
"You say this will be ready to open this on Tuesday?" asks Mrs PD faintly, as we stumble around cables and piles of timber, not to mention the bypassing of a large hole in the floor, in order to visit a gloomy 1950s walk-in meat chiller, complete with giant fan and meat hooks.
"Sure we will, Mum," says her son heartily. Is he thinking of getting Mayor Boris to cut the ribbon? "Of course not. I know we will be seized on by the politicians, but TPS is not political. It is communal."
Nevertheless, he's bang on the money politically, what with a push for volunteering from across the parties, and the Prime Minister's call for the "active participation" of the British people to "mend our broken society".
Once you pay your membership fee (£25) and sign up for a four-hour shift, you will be part-owner of TPS. You will be able to vote on what foods are stocked, and help make decisions on how it's run. You might also find yourself on TV, thanks to a Channel 4 documentary series that (of course) is following the birth of the store.
But running a supermarket with volunteers, however keen, is just not the same as having an army of paid workers, and Potts Dawson, who has opened two London restaurants, knows it. "Hmm," he says, as I rather ineffectually start to clean a window. "I always say that a volunteer takes about three times as long as a professional will to manage a job." I stand back from the window and survey a large area of smears. "I've just cleaned that," hisses Nuala in my ear.
Plus, what happens if the membership is flooded with Peta-style vegans who won't tolerate stacking The People's Milk? "Well, if the membership wants it that way, then that's how it will go," says Potts Dawson stoutly. "But the Board has the power to overrule decisions if it's felt they will undermine the working of the supermarket."
The idea springs from an existing co-operative model in America. Park Slope in Brooklyn, New York, is a co-operative around 25 years old, whose 6,000 members all put in two and three quarter hours a month in order to shop there. Web designer Cathy Clarke has been washing floors and putting out the rubbish at Park Slope for the last seven years.
"I love it," she says. "But then I am like a weird person, I like to clean." And in recession-hit America, the price difference makes a huge difference. "Most stores in the States have 100 per cent markup," she says. "Park Slope marks up by around 20 per cent. In a health food store, a loaf of bread which would costs $3, costs $1.50. An avocado which could be $3 would be $1."
However, as Clarke explains, even though volunteering brings its own feel-good glow, you can't assume everyone in there is a Good Samaritan. "There is a lot of theft at Park Slope," she says. "It's pretty depressing. Cashiers have stolen significant amounts, and have been arrested. People steal food. People sign in, and then don't do their shift." What happens to them? "They eventually get caught and are brought in front of the Disciplinary Committee. They are usually expelled. It sounds harsh, but we are only talking about working for two hours 45 minutes a month."
Even taking holidays is frowned upon, although this is probably no big deal for hard-working New Yorkers, long used to only two weeks of paid holiday every year.
"I wish London good luck with its experiment," says Kristin Miller, 52, who cuts cheese on the deli counter, "but given your British tradition of holidays I think you might have to institute vacations." Judging from how Miller sees it, volunteering to work in a supermarket is not a fun thing, like a sponsored bounce. It's tough. "Over the 20 years I have been there I have occasionally left, because working there has been harder than I could bear," she says.
What happens if you skip your shift? Bad news. "For every shift you miss, you have to do two to make up. The policy is that scheduled time is worth twice as much as unscheduled time," explains Miller.
Having signed up for four hours of cleaning next Tuesday, I'm relieved to discover Potts Dawson is toeing an altogether more gentle path. People can stockpile their hours prior to a holiday and get a reminder call before their shift. Furthermore, there is no talk of a Disciplinary Committee, although everyone working on the tills will need professional references. He is allowing for a 30 per cent no-show from volunteers, and intends to plug the gap with 18-24 year olds on the Future Jobs Fund.
Indeed, for all his Tigger-like enthusiasm, you wonder if Potts Dawson might be thinking that we Brits are pretty rubbish about sticking our hands up and joining in. He needs 500 people to make TPS work, but so far only has 110 signitories. "People keep on saying 'I can't spare the time' and 'What's in it for me?'," he says. "The minute they ask 'What's in it for me,' you know there is no point explaining the point."
Adam York, who runs the Unicorn Grocery in Manchester, a 40-member strong co-operative, is somewhat more realistic than Potts Dawson about the likelihood of people wanting to sweep the floors, or stack Baked Beans, of a night. "It is not easy to recruit motivated people," he says. "Culturally, working in the food industry is not popular. We want people who are interested in the rights and responsibilities of owning a business. And the aspirations of the co-operative movement doesn't necessarily meet modern cultural aspirations."
Rubbish, says Potts Dawson. It perfectly meeets them. This supermarket will be communal, it will be friendly, local, cheap and democratic. Rather like a 1950s Tesco, in fact. Does he think it really can take on the modern day giants? Why not, he says. In the meantime, if you want to cut those food bills, and are relaxed about stacking pots of Danone in a chiller cabinet for four hours every month, your time has come.