It's hard to read these highbrow heisters

Why have I just spent 20 minutes shadowing a respectable-looking man with a newspaper tucked under his arm around a small bookshop? Well, firstly, I work in this small bookshop, and secondly, I think he may have been trying to steal a Penguin edition of Saki short stories.

He was probably an innocent browser, but from a bookseller's point of view, he looked like a man who was waiting for the right moment to slip a short story collection beneath a newspaper tucked rather too firmly under his arm.

Somewhat naively, as a new bookseller, I didn't think theft would be a big problem. I imagined my biggest difficulty would be being able to keep up with our incredibly well-read customers. However, the reality is that most bookshops have to write off thousands in their annual budgets to account for theft. And it's not the obvious wheeler-dealers and petty criminals whom you need to worry about. In fact, book thieves make you realise that you're not as good at judging a book by its cover as you might have thought. Often that dishevelled old gentleman you've been keeping an eye on, who's been muttering to himself and constantly reaching into a bag to find his reading glasses, turns out, when you chat to him at the counter, to be the agent for a Booker Prize-winning author.. Meanwhile, the fresh-faced twenty-something whose lovely brogues you've been admiring takes advantage of your sartorial respect to nab an art book.

What I've noticed is that the books we have stolen are at the more literary end of the spectrum. One feels that the thief is going to take them home and read them, not just dump them in the bin in a post-klepto depression. Paris Review Interviews Vol. 2 and Crime and Punishment was a rather intellectual haul just the other week. So is it only thrilling to steal quality literature?

Across the Atlantic, New York booksellers have noted for some time that it is Beat generation and cult writers such as Bukowski, Kerouac and Burroughs whose work seems to be taken most frequently. But what of London's nimble-fingered?

Chatting to booksellers in some of central London's larger bookshops I discover that it is still the A-Z that is the most-stolen book, closely followed by popular-trade paperbacks. At Foyles, however, the shoplifting is more literary, with a staff member telling me she's recently noticed that a lot of poetry volumes are mysteriously disappearing, and she suspects that plenty of literary fiction is being nabbed as well.

In general, though, it is the smaller, "curated" bookshops where you find the more discerning thieves. A bookseller at Broadway Bookshop in Hackney tells me it's a significant problem, with their top steals being Penguin and Wordsworth classics. Similarly, while Eastside Books in Brick Lane loses the A-Z it also loses Dostoyevsky, and booksellers at the stylish Lutyens & Rubinstein in Notting Hill started to realise theft was becoming a problem when an original Hugo Guinness print was actually stolen off the wall. (For your interest, CCTV has now been installed.)

So innocent book-buyers out there, take note: never walk into a bookshop with an open bag, on the phone, or with a newspaper tucked under your arm. If you do, you're likely to be followed around by a worried bookseller who'd much rather leave you to peacefully browse.

Meanwhile, it's worth remembering that although he penned the words to the most famous song about shoplifting ever, in an interview in 1987 Morrissey claimed he'd never stolen anything from a shop. So I'll send his message to shoplifters of the book world who may be hovering by a door as I type, waiting for the right moment to slip a volume into their capacious plastic bags. Just, "Hand it over, hand it over, hand it over... "

Anna Goodall is the editor of Pen Pusher Magazine and a bookseller at Clerkenwell Tales in London