Cornish dialect
A long time ago, people in Cornwall spoke the Cornish language. This is a language similar to Welsh and Breton. After a while, people speaking English came into Cornwall, and the Cornish people started to learn English. They didn't speak in exactly the same way as the people they learned English from, instead they spoke in a distinct way, the Cornish dialect of English. Eventually they forgot how to speak the original Cornish language by about the year 1800.