Oxfam is the largest retailer of second-hand books in Europe, selling around 12 million per year. Most of Oxfam's 750 charity shops around the UK sell books, and around 100 are specialist bookshops or book and music shops. A typical Oxfam bookshop will have around 50 volunteers, as well as a small number of full-time staff.[1] The charity makes around £1.6 million each month from book sales.[2]
Books are donated directly to shops by the public, or through Oxfam "book banks" in convenient locations around the country. The profits of the book sales support the work of Oxfam.
(Description taken from Oxfam Bookshop Wikipedia page
https://en.wikipedia.org/wiki/Oxfam_bookshops)