The UK is somewhat crazy in terms of measurements. They have speed signs in terms of miles per hour (50 mph) but then the directions are given in kilometers - it is 50 km to that town.
We even saw a sign that mixed up both - it was a maximum height sign that said something like 7 meters, 5 feet.
When I first got in my car, I thought that the speed limits would be km/hour and I saw 50 and wondered, that is pretty dang slow. I had no idea which one so I kind of went in the middle of both until I confirmed it. It seemed very strange, eh?