I see we have not had an answer to the original query about whether Na(r)von could be a contraction of Carnarvon. I am not near enough to personally know the area but it doesn't 'feel' right. On my nearest coast they might shop in 'the Bay' (meaning Colwyn Bay) but I have never heard the three syllable Llandudno abbreviated. Elsewhere it seems more common to say 'the Llan'(used to roughly mean village) without specifying Llan-whichever is meant.
Gadget I think your area of Wales was further away still from Carnarvon but would you agree that it would be unlikely to be shortened to Narvon?
