Trewsbury looks interesting! To me, anyway, being sited so close to the source of the Thames...
Some years back, I worked - and pretty well lived - in Lechlade for a couple of years, but didn't have transport of my own, and had little spare time to go exploring. My interest in the old stuff, and wells, hadn't really taken off at that point, anyway. I wish it had. There's some really interesting and historic places round there! It was from there that I first visited Uffington White Horse, with a friend who had a car, on the Summer Solstice of 1991. The first of many visits. Fabulous place for a day out...
Lechlade, being the furthest navigable part of the Thames, always interested me anyway. A friend and I took a small 2-man boat as far as we could one day, but were thwarted a short way up by some thick weeds! A lovely part of the country though. Typically postcard-English, I'd say, with it's rolling green fields, stone houses and profusion of antique shops! ;) And it is, of course, home to the Lechlade Cursus.
Ackroyd's book is fantastic, by the way. It spans many timelines, so will appeal to anyone interested in any period in time. There's some great nuggets of information, such as the time when, in 1014ce, King Olaf of Norway threw cables connected to his ships around the pillars of London Bridge, and sailed his ships away, pulling it down, thus giving birth to the well-known song "London Bridge is Falling Down"!
G x