After some umming and aahing I wondered about Catherine Fisher, but she's not famous enough, apparently - at least yet. Dylan Thomas? But he did a lot of networking, and indeed living, in London and elsewhere, didn't he? Owain Glyndwr, perhaps? Oh darn - even he spent quite a bit of time in England, IIRC. Same with Giraldus Cambrensis. Then there are Taliesin, Gwydion, Pryderi, and all their chums from the Mabinogion. But I think being mythical probably disqualifies them.
Oh gosh, I feel there must be hundreds, but my mind's a blank!