It is interesting, there was a thread earlier on today about Cornish names. Cornish is a dead language as there are no native speakers left.
It is very similar to Welsh and also to Breton. Breton was also 'put down' but the French speaking French.
When onion sellers used to come to wales (this sounds like something out of Little Britain I know )from Brittany my Grandmother could speak to them in Welsh and they would reply in Breton. they could just about understand each other.
When I went on holiday in Brittany I was unconsciously translating lots of the place names, as they are so similar to Welsh.