Interesting Kop. The Americans love the old imperial system...as do I. It did cause a space rocket malfunction though I seem to remember. A joint American/European venture went pear shaped when the Americans were using imperial measure and the Europeans metric. Cut you mum some slack today, she will be tired out and wired at the same time if she feels anything like me. I was out of the house at 6.20am and stepped back in at 10.45pm with no break or time out. Food and drink on the go and no outside contact. Then couldn't sleep for numbers going through my head all night.