Way back when I was an apprentice, I had two 6" pocket rules, both were Moore & Write (English). One had incnes on both sides in various combinations of 16th's 32nd's 64th's and 128th's. The other, again in inches on one side with 10th's and hundredth's, the other side was metric with 10nth mm on one edge and hundredth's on the other edge, very fine engraving indeed. Even back in the early 1960's while we were still very much in the imperial world we had to be able to work in metric, as the factory I was at we were the importing agent for two European cars.
Australia began converting to full metric in 1966, first with our money, then weights and measures. it was done in a very progressive way, such that most people had very little difficulty with it except a few of the very elderly. It was mde very simple by at first price tags were printed with the price in the old system of pounds, shillings and pence in large numbers and the new price in Dollars and cents in small numbers then over time the sizes changed over, and eventually they stopped putting the old price on at all. It workd very well.
Then around 1971 we started introducing metric measurements so feet and inches gave way to meters and mm. Then pints and gallons etc gave way to to Liters. it was made easy by the fact, that for some years before changeover date all new measuring devices were calibrated in both systems, so by the time change over came we were pretty much ready for it. I must say that it was the best thing we ever did, life is so much easier in every way.