Saturday Night: Dancing in the aisles at 7-11

'I'M GOING to complain to the bloody old boss, I am,' said a crumpled old woman with a woolly hat pulled snug over thin grey hair, her skinny legs in orange tights tapering into a pair of scuffed high heels. She was carrying an inordinate number of plastic bags, an umbrella in her armpit, and was wrapped against the cold in a long check coat that had seen better days.

'That change isn't right,' she muttered as she counted her coins at the counter. Gently, she was put right on the matter. 'Oh, is that the new 10 pence piece. I thought it was a five. Aren't they small? Mind you, everything's smaller these days.'

The staff at the 7-11 shop on Westbourne Grove, west London, are quite used to Mary. She comes in most evenings and chats a while with them and customers. 'She's on her own,' said Nega, a gentle Sudanese, in charge of the till that Saturday night. 'What can we do with her? She doesn't cause any harm.'

Mary had pottered off to the far end of the shop where Elsa was pricing the biscuits; Elsa, aged 24, had arrived from Eritrea just over a year ago. Mary was giving her elocution lessons. 'You see,' Mary announced to the rest of the shop, 'I went to grammar school, so I know how to talk.' Elsa just smiled and listened, which is all Mary wanted her to do.

At the the front of the shop, the customers came and went, each movement announced by a sharp bleep from the door bell. A couple kissed by the refrigerated cabinet before choosing a bottle of wine, pasta and pesto sauce: they were going to spend their Saturday night in. A smart gent came in to pick up some tonic water: he was entertaining at home. A short man in a grey coat wandered around the shop, paused by the porn mags, then shifted off. A group of German tourists argued the merits of toasted cashews and dry roasted peanuts. Two girls in Gucci clogs and make-up that glowed orange under the neon lights were choosing lollipops. 'We've got to have something to suck while we're E-ing,' said one, sweeping back her thick blonde hair. 'Oh yerr, you are organised,' said the other, skidding in a puddle of lemonade.

'Do you take Switch?' asked a cashless Sloane in a Norwegian fisherman's sweater, attempting to pay for a bottle of 'vodie and a packet of Silk Cut'. His girlfriend, with a skiing tan, had to part with a cheque.

There was a swift trade in semi-skimmed milk and chocolate bars. 'That's what most people buy in the early evening,' said Nega. 'After about 11 when the pubs shut, we get people dancing in the aisles buying those meat pies.'

Mary was back. 'What's the price of this bread?' she asked, searching the wrapper for a tag. She sought the opinion of all around her. 'I haven't got the foggiest,' said an American, clutching her small son who had on a plastic policeman's helmet. Mary settled on a price, made as if to leave, then turned and said with aplomb: 'When I win the pools, I'm going round the world, you know. I'll put on my snow boots and my top hat and I'll be off.'

Elsa, who had been so preoccupied with Mary that she had forgotten the bread in the oven, sprinted the length of the store, covering her mouth in horror. Down in the bowels of the shop, she hauled hot baguette after hot baguette out of the oven and slipped them into their wrappers. They smelt warm and delicious. 'Would you like some?' she offered. 'I'll pay for you to have some.' I said I was just about to eat.

It was 3am when I came back, and the shop was full of punters who couldn't sleep. A group of Spaniards was buying some Galaxy chocolates. A custody officer, on duty until 7, was stocking up on crisps. A boy with long hair was heating up an apple pie and custard in the microwave. A hippie came in for more Rizla and some Frosties. 'I've been smoking too much and I have really bad munchies,' he sniggered. A man with dirty hair and nicotine-stained teeth, who was helping himself to some white coffee with three sugars, barked to be left alone. Others were buying the Sunday papers.

I had expected some drunks, and as I reeled my way around the aisles searching for a pie, I suddenly realised that I was the most inebriated person in the place. The late-shift cashier sighed as I paid. He'd seen it all before.