It's market day. I put on a cloth cap and set off to work. The stall is in Lyric Square, Hammersmith, a windswept plaza that must have looked cool on an architect's Mac and is now a dreary between-zone of coffee chains and lunch-hour sarnie seats.
Thursday's farmers' market is probably the best thing that ever happened to it. There are about 15 assorted stalls: Moroccan pies, Portuguese tarts, suckling pig. Pride of place is Perry Court Farm's fruit 'n' veg stall, and here I find Heidi Fermor. The farm, near Canterbury, is family-run and Heidi heads its retail operation.
I instantly know she's going to be a good guv'nor. Although she gets up at 4.30am, lugs fruit, veg and heavy awnings into a van and drives to an ugly car park costing £13 a day, all in the name of serving the rich mix of Hammersmith humanity, she remains a beaming beacon of diplomacy. Heidi's super-efficient assistant Joanna is tall, thin and inscrutable and comes from Poland. A pair of Clint Eastwood-like narrowed eyes is all she needs to communicate with even the most brazen bargain-hunter.
First task is to spread out our wares. Plums, greengages, cobnuts, chilli peppers like Satanic horns, the alien lifeform that is kohlrabi - the whole home-grown schmeer is here. 'You're supposed to line them up level to the tummy button and the nose,' advises Heidi. 'They say that's the way to shift them.'
A market stall has to appeal to all senses, so it's a relief when some tourists take photographs of ours. The apples - Perry Court's chef d'oeuvre at this time of year - are upfront: £1.50 for one bag, £2.50 for two, £3 for three. Heidi's got her progressive pricing policy down pat. She routinely asks the punters if they'd like two and, by the end of the day, I'm doing the same.
Heidi fits me out with an apron loaded with pound coins in one pocket, silver in the other - and I'm trading. It's compulsive. As Heidi points out, you have three seconds to get a potential customer's attention. 'I'm always catching people's eyes,' she says.
This being a posh farmers' market rather than a costermongers' carry-on, things are more genteel. There's no shouting 'Luvverly toms, mum' at passers-by, and the labelling is by means of a gastro-pub-style blackboard without a single grocer's apostrophe.
As the morning wears on, the punters emerge. 'Any garlic?' asks an actorly type, perhaps on a break from rehearsals at the Lyric Theatre. Sadly there isn't, but fruit juices are shifting fast today. That's the thing about market trading, confides Heidi: 'You get instant feedback.' And like all smart businesspeople, the Fermors know that product development is crucial these days. Heidi's son Charles has developed a line of apple crisps. Dried rather than fried, they're tasty and much better for you.
Heidi also knows the value of keeping up with the competition and I'm despatched to check prices at the nearby Sainsbury's. It works - back at the stall, a customer baulks at the carrots: £1.50 a bunch. 'Cheaper than Sainsbury's,' I retort. She buys.
The lunchtime peak approaches. Joanna's on fire, Heidi takes care of three customers at once. I keep forgetting the prices. This job is all about mental arithmetic. 'I hope it'll help stop me going senile,' says Heidi. 'It's like doing Sudoku all day.'
A lovely lady plays with the Victoria plums a little too long, and I realise why greengrocers hate ditherers. Also on the stall-holders hit-list are squeezers: older women who tut-tut as they prod away. Others negotiate as if they're at a UN summit. 'All zese aubergines: three pund,' says a ruthless young Russian. Putin would be proud. A chap in a suit does the whole transaction while talking loudly on his mobile: problem. A cute girl wants leafy tops free for her guinea pigs: no problem. The men call me 'mate'. Several grab apple slices from Heidi's tasting table and move furtively on. Scrumping is alive and well.
Abruptly, the rush is over. I've got several rumpled notes in my apron, but Heidi never counts money on the street. At 3pm we take the awnings down and lug them to the van, parked in a distant loading bay. Back and forth 10 times, it's back-breaking. But for the farmers, there's no alternative. As Heidi relates, all was fruity in the garden of England 'until Mr Supermarket came along. People went bust. We had to find another plan.'
Heidi is shy about the day's take. My guess is about £600 gross. Heidi's so nice I don't like asking what she pays staff. 'Well above the minimum wage,' she says. So it won't make you rich, but it'll do wonders for your mental arithmetic and your biceps, and put a canny glint in your eye. You could do worse.