A reader has taken me to task for using metric measurements in answer to a recent query, when I said that there should be a gap of at least 150mm between downlighters and loft insulation. He thinks that most readers of The Telegraph would have difficulty visualising 150 millimetres, and that I should rather have written 15 centimetres or, better still, 6 inches.

Remarkably, this complaint about metrication is only the second that I have received in five years of writing this column. You might expect Telegraph readers to be a pretty conservative bunch on such an issue, but the indulgence shown me thus far makes me suspect that there is less opposition to metrication than is sometimes supposed.

When I started writing the column, we had some discussions about this. Telegraph "house style" is to use imperial measurements. I argued that the building industry in Britain has been metric since 1970, that materials are sold in metric sizes, and that all the relevant standards and regulations are metric, so it would be difficult - and possibly misleading - to slavishly convert them all. The editors very kindly - and sensibly - agreed to allow me to use metric, and left it up to me to decide when, for the sake of clarity or comparison, I should add imperial equivalents.

When my Telegraph book was published, we agreed on the convention that where a reader's query uses imperial measurements, these are left as written, with the metric conversions in brackets, and my answers are written using metric only.

As well as offering the advantage of global standardisation, metric measurements are less prone to errors. I once employed a carpenter who insisted on working only in feet and inches, which I think he intended as some kind of political statement. Unfortunately his numeracy and tape-reading skills weren't up to it, and he was forever getting his seven-eighths mixed up with his fifteen-sixteenths. Millimetres would have made his life a lot easier, and kept him in a job.

There are some common misconceptions about metrication, which contribute to the general reluctance in Britain to embrace it. One is that it is a fiendish plot by the European Union; but the metric system is also used in most Commonwealth countries, former Eastern Bloc countries, and much of the developing world. So readers are quite at liberty to use metric measurements and remain politically Euro-sceptic.

Another is that metrication is a lefty/liberal plot. In fact, the first letter of complaint I had, four years ago, told me that if I wanted to use metric measurements I should "go and write for The Guardian". At the time, however, The Guardian's house style was firmly imperial, and, in common with most newspapers, its journalists are only now struggling to get to grips with grams and litres.

Most European countries use metres and centimetres, but the British building industry measures everything in millimetres, thus doing away with the potential confusion of decimal points (for example, 25mm rather than 2.5cm). On construction drawings you will also often find that the comma after thousands and the "mm" after all measurements are omitted. So a town house is 5500 wide, a door opening is 2100 high, and a kitchen worktop is 600 deep.

One thing I have never understood about the anti-metric movement is why it has such limited aims. I mean, why stick with feet and inches when you could campaign to restore chains, links and nails? And let's face it, we all knew where we were with the rod, pole or perch, didn't we?