Two books bestrode my childhood, and made me the man I am: The Magic Bridle, a collection of British and Irish myths retold by the folklorist Forbes Stuart, which ignited my six-year-old imagination in 1974, and Mysterious Britain by Janet and Colin Bord, published two years earlier, and part of a then burgeoning bookseller phenomenon of often unreliable Earth mysteries compendiums. Nonetheless, they set this particular boy off, seeking out ancient sites whenever possible. Now everything has wilted but I still have calves of iron, and I can identify the outline of a hilltop earthwork from a moving car on a motorway as surely as a falcon seeing a field mouse 500 feet below.