Mark Forsyth’s funny and affectionate tribute to good bookshops is little more than a pamphlet, but its infectious enthusiasm will delight those who know that nothing beats a good bookshop when it comes to discovering books you never knew existed. I think he would be pleased to know that I had never heard of The Unknown Unknown before I spotted it by the cash desk of one of the world’s best “good bookshops”, Hatchards of Piccadilly. It was an unknown unknown.