] I noted with interest that on the 1790s map, Ashe and Deane were spelt without the final "e". I wonder if (more generally too, of course) the last - now useless - e was added as an assertion of age; or perhaps just a change of fashion - just as Molly, Minny, etc. were not long ago more fashionably spelt Mollie, Minnie.

I think this map made, presumably, by a private individual for commercial purposes, relies on the pronunciation of the times. Spelling was still not very systematised then, and if the the e wasnt pronounced , it wouldn't have been printed. Getting all wound up about aged spelling, and saxon roots was very much a Victorian thing, too- as you say, a fashion. Nowadays the spelling of place-names has been thoroughly fossilized!