One Boterel died in Spain in 15th century. I had despaired of ever finding out how and why. Quite by chance, I came across a town called Botarell in Spain, and am investigating a possible connection. It's almost certain that some of the Bottrills were involved in the Hundred Years' War, and may well have supported the Black Prince in his foray into Spain.
So that's a town in Spain that may be named after the family, and of course two in England - Aston Boterell in Shropshire, Boscastle in Cornwall. I haven't yet found one in Brittany.