Quote Originally Posted by Morris at Heathfield View Post
The more recent grouping divides the languages into Continental and Insular Celtic groups, with the Goidelic and Brythonic languages comprising the Insular group, and the Celtiberian and Gaulish languages comprising the Continental group. In this grouping the importance of the *kʷ to p and related sound changes are given less importance than certain features which are shared by those Celtic languages spoken on the British Isles.
That may make sense more than just linguistically. I haven't read the whole thing yet and haven't looked at it for weeks, but I seem to recall this book mentioning that there also is no genetic linkage between the British Celts and the Gauls. . .though there is between Ireland and Spain.