One of my favourite second-hand book shops is Oxfam in St Giles, which next month celebrates its 21st birthday. In 1987, staff member Vera Jefferson came up with the idea for the shop because she was tired of lugging books around to book fairs. Over the past two decades, the shop has raised more than £4m and is one of the top three specialist Oxfam book shops in the country. Next month, volunteers will celebrate in style by staging an author's talk on November 14. Philip Pullman is one of the speakers at the Quaker meeting house in St Giles, and tickets for the talk are on sale at the shop. The following day, at noon, Sir John Mortimer, the author of those Rumpole of the Bailey stories that made me chuckle, will cut a cake at the store. Authors have been encouraged to hand in signed first editions to help the Oxfam cause in the run-up to the celebrations and I gather this is now a daily occurrence. I know a little bit about the work that goes on behind the scenes because I do a spot of volunteering myself, although I must stress that I am an absolute beginner compared to some of the stalwarts who have given dedicated service for decades.

The particular task I have been allocated is assessing a book's value before deciding on a price and during a brief sojourn in the basement the other day, a cornucopia of treasures came my way. Topping the bill was an 1841 compendium of the humorous magazine Punch, which I believe was the first year the publication came out, so this could be worth a couple of hundred quid at auction. Then there was the first English edition of Dr Zhivago, in dust jacket, from1958, which could fetch £50. There was also a pile of old Rupert annuals in pretty poor nick but the 1969 edition, featuring Alfred Bestall's iconic Rupert and Raggety tale, brought back some happy memories and I hope the slightly unusual stories will amaze and delight a young customer. My only disappointment was that first editions of Rudyard Kipling's poetry collections, The Five Nations, and The Seven Seas, are ten a penny on the Internet, so they will not fetch more than a fiver. But it all goes to help a very good cause, so if you are passing, why not call in and pick up some reading matter?