Norwegian Wood

The Norwegians had a unit of length called a 'tomme' or 'thomla' based like the inch on the length of a man's thumb.  However, being 26.1mm, the tomme was 3% longer than an imperial inch (25.4mm) and the reason is not due to error.

There has historically been a large trade in timber between Norway and UK. When wood dries it contracts by 3%, so if it is cut to 4 by 2 tommes it ends up as dry timber at 4 by 2 inches.

Of course the millimetre has taken over now in both countries, and spoiled a good bit of history, but not spoiled a good story.