Just before Christmas, I visited 30 different London charity shops, donating a single signed and numbered copy of my murder ballads book at every one. Then I posted a set of photo clues on my website and challenged readers to find the shops - and books - involved. You'll find full details here.

Anyone finding one of the 30 special copies has the chance to buy it at a bargain price, while also knowing their money goes to support the charity’s valuable work. I didn't tell any of the charities what I was up to at the time, but I've since heard from many of them supporting the idea.

Our first winner was Michael@Catch22, who found and bought a special copy of the book at Cancer Research in Highgate. "I was delighted," he told me. "Best three quid I ever spent. Book is number 19 out of 30.”

So far, that's the only one of the 30 books that's been definitively accounted for, so there's still plenty to play for. This Twitter account will keep you up to date with new developments.