Used to go here regularly when worked nearby. Staff friendly, and lovely ambience, complete with creaky floorboards.
The stock turnover was pretty high so I could come back each week and buy more books I would never have time to read.
Popular and obscure, it's a fascinating place to browse. Particularly good for the variety of non-fiction - Law and Politics unuaually well-represented - not too surprising given its lication. Books are not ultra-cheap, but seem reasonable (it is a charity shop). And there's a market just outside too., and an Italian Pizza/Coffee place nearby. Bliss.
Oxfam is a development, advocacy, and relief agency working to put an end to poverty worldwide. In partnership with local groups, they work with poor people to help them help themselves. The Oxfam shops sell second-hand clothes, books and bric-a-brac as well as trade fair goods to help raise money for the charity. This particular branch specialises in second hand books, music and videos.