The Bookshop at Guildhall Library
If you are going on Tinas next tour around the Guildhall on Thursday, I reccomend a quick browse around the new Guildhall Library bookshop. It may be small but it has a fantastic selection of books about City of London history, historic maps and a postcards featuring the library collection. The only risk is you will end up buying more than you bargained for.
The bookshop is open at the same time as the library details here