Welsh
Welsh comes in three flavours: Welsh the language, Welsh the people who live in Wales and Welsh the language spoken by those Welsh people who live in the Northern bit of Wales.Welsh the language
The the Welsh mostly speak English as well as Welsh due to the concerted efforts of several hundred years-worth of occupying Englishment attempting to stamp out the language because nobody could get a decent reception on the TV.
The language Welsh is thought to be one of the oldest languages in Europe, and trumps the other Celtic languages (such as Gaelic and Cornish) because it stubbornly refused to die out. Nowadays people are rather more enlightened about such matters, and have developed digital TV, with the result that Welsh is now being taught in most Welsh schools.
Such regional variations as exist within the Welsh language exist because the middle of Wales contains a large number of mountains, and the people of North Wales have developed the Welsh-langauge equivalent of a Birmingham accent in comparison to the South.