From 1 October, half a pound of butter will be sold as 228 grams. A square yard of carpet must become a square metre. And a pint of shandy will be consigned, like mead, to the nostalgic drinker's memory. European legislation decrees that all goods and pre-packaged food must be sold in metric measurements; come the millennium, this will include all food sold loose. By the turn of the century, a pound of King Edward potatoes and a quarter of sherbet drops will be as redundant as a bushel of barley.
"This is like a sledgehammer coming down on us. I still get customers coming in who talk about shillings - they aren't going to know what this is all about, are they?" Paul Reynolds, the rotund and rosy-cheeked owner of the Allington Farm Shop inWiltshire, is sorely provoked. The small roadside store sells fresh produce, cheeses and meats packed by Mr Reynolds.
"I shan't be fit for 1 October. We've got to change all the scales over, and that'll cost me a grand. I've just had new labels done to last me the next year, and now they won't do. It's a mess.
"Take turkeys. People know they want a 15lb turkey or a 20 pounder, or whatever - they don't know what that is in kilograms, do they? And when people go home to their Mrs Beeton cook book and read '20 minutes per pound', it won't make any sense."
European influence is unwelcome in the Allington Farm Shop. A large sign on the wall declares: "No French produce sold here". Mr Reynolds is unapologetic. "It's not fair. We stood up for the British banger, and managed to make them leave it alone, and now we get this thrown at us."
The earliest standardised Imperial measurements were introduced by royal ordinance in the 13th century, shortly after the Magna Carta. The "Iron Yard of our Lord the King", the perch (later the rod) and the inch - subdivided into three barley corns - all became "Imperial", rather than localised, units.
The bushel arrived in 1701, and in 1824 the gallon was standardised in parliament as "the volume occupied by 10 imperial pounds weight of distilled water weighed in air against brass weights with the water and the air at a temperature of 62 degrees of Farenheit and with the barometer at 30 inches".
Metric measures aspired to rather more simplicity. Established in Paris after the French Revolution, their conquest of the Continent was swift, thanks to Napoleon's military successes. But the decimalised method did not reach these shores until the 1960s, when chemists were required to dispense metrically. Imperial measures gradually ceased to be taught in schools, and in the mid-Eighties petrol began to be sold by the litre.
The latest measures on measures hope to banish all lingering imperial eccentricities, and fully metricate the country.
"Well, I'm afraid it just makes it a muddle, really. I have to order my cloth in metres now, but if I measured you up, it'd always be in inches." John Coggin, director of Tobias Tailors on Savile Row, frowns. He has been a tailor for 35 years, and the battered 1930s cutters' handbook at his side works only in inches.
"If I had to convert into centimetres I don't know where I'd start," he said. "All the cutters on Savile Row learnt in inches, and that's how we teach the trade." He picks up a book of worsted suiting swatches, marked, somewhat confusingly, 13oz per metre.
"You get elderly gentlemen coming in wanting a 13oz suit, they've always had a 13oz suit. But it used to be per yard, and they can't understand that they need something heavier now. Soon it'll be in grams per metre - now I know what a 13oz cloth feels like, but tell me it's 400g, and I'm lost."
At an open-air market in Islington, north London, the tone of stallholders is a little less measured. "They reckon in four years' time if some old dear asks me for a pound of apples and I don't say: 'I think you want half a kilo, madam', they can whack me a thousand pound fine and put me in the nick if I don't pay," barks one. "Well, it's completely, bloody stupid."
Supermarkets are completing the process of dual labelling and pricing on pre-packaged foods. The cost of changing scales, labels, computers, training staff and publishing conversion charts and leaflets has, Sainsbury's estimates, cost them more than pounds 1 million.
Only the mile and the pint have been spared metrication's forward march. A special British dispensation permits road signs to show distances in miles, and publicans may continue to serve pints - but only of beer and cider.
"We can't serve a pint of shandy or orange juice and lemonade any more - it has to be 550ml. That's just under a pint, but you can be sure breweries won't drop the price," says Kevin Connor, licensee of the Red Lion pub in Manchester. "Our bar staff can't spend all night saying: 'You mean 275ml, sir', can they? And what about all our glasses? They'll be the wrong size now. It's ridiculous. You can't mess about like that."
Imperial measurements were introduced to iron out regional variations and facilitate fair trade. Seven centuries on, metrication shares the same goals. The ends are estimable, but the process painful - and the loss, in colour and language, lamentable.
"Well I dunno, metric don't sound like much, does it?" shrugs the market trader. "There ain't no rhyming slang for kilos and grams, now, is there?"