The trouble with metrication enthusiasts is that if you give them an inch, they’ll take a kilometre. Britons have, slowly, grown used to temperatures in centigrade, and indeed have embraced those at the lower end of the scale with enthusiasm: minus 6C sounds colder than 21F. But at the top end, Fahrenheit refuses to die — “94 in the sun! What a scorcher!” is a better headline than “Temperature reaches 34C”. Thanks to Brussels, we are also now obliged to buy and sell petrol in litres, while still calculating the efficiency of cars in miles per gallon. So attached are Britons to some of the ancient measures, however, that the Government had to seek dispensation from Brussels to allow milk to be delivered, and beer to be pulled, in pints. And there is no enthusiasm to break the historic links between time-honoured pastimes and their measures: ships and fathoms, horses and furlongs, whisky and tots.

Logically, it is hard to argue in favour of retaining imperial measures: the word itself suggests an anachronism. But the yard, foot and inch are based on human dimensions and are, therefore, rooted in history. The metre, by comparison, is an abstract construction, defined by French scientists (inaccurately) as one ten-millionth of the length of the Earth’s meridian along a quadrant. It began life in Revolutionary France alongside rationalist calculations that also saw the division of weeks into ten days and days into ten decimal hours, a ludicrous experiment that lasted barely seven years.

Forcing the pace of change rarely works, though a younger generation, schooled in metric, now largely think in metric. Few now know the once essential mnemonic “George III said with a smile, ‘1,760 yards in a mile’ ”. Usage will determine change: and why can Britain not keep both systems going for a decade or two? Weighing ourselves in stones is as quaint as it is harmless. The UK Metric Association argues that, with a stalled reform, Britain has now the worst of both worlds: a hybrid system that is as confusing as it is expensive. Resulting mistakes can be costly: six years ago Nasa lost a $125 million Mars spacecraft because of a mix-up between imperial and metric units in its construction.

The association claims the Government lost its nerve over the conversion of road signs as long ago as 1973, and has since exaggerated the cost of transition as a tactic. It is a complicated issue, but the minds of the young are surely improved by the agile mental arithmetic imposed by two, in a sense competing, systems, and not all of our cultural quirks need to be (allegedly) simplified out of existence.