Do the British regularly not use the metric system? In Harry Potter, wands are expressed in inches, and when Harry falls off his broom in PoA, Ron describes the height in feet. I'm trying to remember now what units of wet and dry measure are used for potions ingredients. And in Discworld, Carrot is described as 6 feet, or 6-foot-6, depending on which book you're reading. So explain yourselves, oh Brits. Why make fun of America not switching over when the UK hasn't switched over entirely, either?