This reminds me of a theory my American friend Jim had about Welsh - that the all the new words William the Conqueror brought over led to a shortage of vowels, so the English stole them from the Welsh.
Hence the Anglo-Welsh wars.
I thought it a bit fanciful, but Jim may have been onto something after all.
"They may take our lives, but they will nevyr tyk ywr vywlls! wh, bwggyr!"
Epi