Cornwall has its own language, because it’s a fiercely independent county (some want it to be a separate country!) that years ago, only spoke Cornish. It was not long ago that the last person died, who was a native speaker, never learning English until she was around 19.
People think that it’s Gaelic, but it’s not. Cornish is more related to Welsh, and people in Brittany and some parts of Argentina can all understand each other. People who hear it, say that it sounds ‘like someone talking backwards’ or ‘like English to a person who doesn’t understand the language’. You can buy buy Cornish language books online, if you can’t find them in local shops. One good book for anyone to have a go is Teach Your Dog Cornish!, an illustrated retro-style book to learn 60 words and phrases, to practice your Cornish with your furry best friend.