It was nice to see the old folks looking happy. There were smiling faces in Tesco, and the supermarket attracted 50,000 extra customers yesterday as it returned to weighing produce in pounds and ounces, in defiance of the "metric only" rules that became compulsory throughout the land at the start of this year. A victory for imperial weights and values!

It was nice to see the old folks looking happy. There were smiling faces in Tesco, and the supermarket attracted 50,000 extra customers yesterday as it returned to weighing produce in pounds and ounces, in defiance of the "metric only" rules that became compulsory throughout the land at the start of this year. A victory for imperial weights and values!

Somehow, for me, it's not that simple. I'm a member of that generation of in-betweenies who can just about measure the new kitchen units in centimetres but struggle with the idea of a 2.4-metre shark which still ought to be eight feet long.

Numerous holiday expeditions to French markets have made me at home with 200 grams of butter and half a litre of milk, but I can't quite get my head around my target weight on the bathroom scales being 82 kilos. And though I'm accustomed to the idea that 200C means Gas Mark 6, I still go blank when people come back from Greece and say, "It was 30 degrees!". Is that supposed to be good or bad, I wonder as I start to do the "nine over five plus 32" computation. (Or is it five over nine minus 32?)

But pounds are for wimps and nostalgists. The metric system is, after all, the appropriate measurement for our rationalist, scientific, post-Enlightenment times. Tens are so easy to divide and multiply.

On paper, perhaps. But weights and measures were devised in the marketplace. We have 12 inches to the foot and 16 ounces to the pound because they can be divided again and again, down to a single unit, where decimal division gets tricky when it gets down to five.

"I'll have half of that; no, a quarter will do," makes life easier than dividing from a thousand. In any case a metre is now officially defined as "the distance travelled by light in a vacuum in 1/299,792,458 of a second".

There is something even more elemental. The pre-metric systems were almost all based on body parts. The basic unit of length in ancient China was the distance from the pulse to the base of the thumb. In Greece it was the finger - with 16 fingers in a foot. (Don't ask.) And the Egyptian cubit, which set the standard for the ancient world, started about 3000bc as the length of the pharaoh's arm from elbow to fingertips - standardised by a royal master cubit of black granite. (It proved accurate enough to build the Great Pyramid whose sides vary no more than 0.05 per cent.)

But the world has always had those irritating people who want to tidy things up. High on the list of jobs of Shih huang-ti, the first emperor of China in 221bc, was unifying the basic units. (He must have been fitting a new kitchen too.)

In Europe in the 9th century Charlemagne tried something similar, without success. Then George Washington, in his first message to the United States Congress in 1790, banged on about the need for "uniformity in currency, weights and measures". Decimal currency they managed, but he and Thomas Jefferson together could not budge the vast inertia that keeps Americans clinging to the old English system of weights and measures.

Of course you can run the two systems in parallel, as, following the best European traditions, Tesco stores are doing. Even Napoleon had to allow that for 40 years in France. The trouble is then half your scientists measure in centimetres and the other half in inches and you end up with your space satellite embarrassingly crashing, as Nasa discovered quite recently.

Perhaps the European Union should direct its attention elsewhere. How about the measurement of time? There's something rather messy about all those 60 minutes, 24 hours, seven days, odd-numbered months and 365-day year.

That should keep the bureaucrats in Brussels going for a while.

p.vallely@independent.co.uk