[QUOTE=Giggleswick;22362522]Bloomsbury has, not surprisingly, some second hand bookshops with a good selection of academic books, including philosophy. Two that I'm familiar with are Skoob, at north end of the Brunswick Centre near the Russell Square tube station, and Judd Books on Marchmont Street, only about a block away from Skoob. QUOTE]

Also, although not a second hand one, The School of Oriental and African Studies has an interesting bookshop, obviously specialized in the continents of Asia and Africa, within the Brunei Gallery premises.

http://www.soas.ac.uk/visitors/bookshop/