Mr Smith goes to . . . the second-hand bookshop

You can't sell a book by Jane Fonda or Margaret Thatcher

You are sipping a latte, listening to a CD, trying to make up your mind which DVD to buy. Where are you? Answer: in a bookshop. Even readers who enjoy the extras of the bookstores-that-think-they're-a-mall could be forgiven for asking if the chains and multiples have lost sight of their core business. This is to say nothing of the lowering truth that the most eye-catching pitches in the shops - in the windows, nearest the doors - are filled not according to the thought and care of the assistants, but carved up between the major imprints, in a kind of publishing payola.

Second-hand bookshops, for all their whiff of the house clearance sale, are a more sensitive barometer of reading patterns. They are the last resting place of the summarily remaindered celebrity memoir, the TV tie-in with the mayfly life cycle, and the experimental novel. Meanwhile, there is a steady turnover of the titles that the reading public actually wants.

In the Northumberland town of Alnwick - otherwise noted for an extraordinary hotel restaurant that is an exact replica of a state room aboard the Titanic - is the Bodleian or British Library of second-hand bookshops. Opened a full decade ago, it anticipated the innovations of the high street bookstore: the coffee (not to mention filtered water from a well); the staff endorsements, in enthusiastic copperplate ("Sterne emerged like a comet on the literary world!"). But the management remembers to put the books first. The shelves are adorned with quotations from literature: Sylvia Plath is provocatively bookended with her one-time spouse, Ted Hughes. Dominating everything is a splendid writers' gallery, the work of local oilsman Peter Dodd. Mary Manley, the distaff half of the husband-and-wife team behind the shop, agonised over who to include in the commission, and who to leave out.

She says: "Salman Rushdie: I have to admit all that business with the fatwa did weigh with me. It's just not on. Plus the fact that Peter actually wanted Salman Rushdie in, his distinctive features a painter's delight." Toni Morrison also got the thumbs-up, "not just because she's a woman (all right, PC) and yes, black (PC), but because (will I never learn to be objective?) a friend once interviewed her and said she was wonderful".

I mention Mary's Barter Books not to puff the place - I paid hard cash for my first edition of Scoop - but for its "notes on incoming books". This is a hilariously unsparing primer on what separates the hot cakes of nearly new books from the frozen gateaux. "Authors who were once very popular but are now less so" include James Herriot, Robert Ludlum, Jeffrey Archer (gasp) and Joanna Trollope (surely not?). Before you clear out your bookshelves and point the car in the direction of Northumberland, here's Mary's full list of "former vogue books", that is, the ones that are now certifiably unshiftable: "Jaws, Jane Fonda Keep Fit, Adrian Mole, Savages, Some Other Rainbow, An Evil Cradling, Taken on Trust, royal books, Margaret Thatcher".