Authors revisit and annotate their own famous work:

“J.K. Rowling had only agreed to annotate a copy of Harry Potter and the Philosopher’s Stone on condition that it was a genuine first edition, from the first print run in 1997 of only 500 copies, 300 of which had gone to libraries. Gekoski had to find one of the remaining 200. ‘So she was quite surprised,’ he said cheerfully, ‘that two days later, I came up with a copy and said, “Let’s go ahead.”‘

“It had cost him £20,000 (he will be reimbursed after the sale). But now, “freely annotated” by its author, with more than a thousand words “on the process of writing, editorial decisions and sources of inspiration …” along with 22 illustrations, it is likely to go for a great deal more.

“Sotheby’s has released a short paragraph to give a flavour of what’s inside – though what she describes is so familiar, it’s already part of JKR mythology. ‘I wrote the book … in snatched hours, in clattering cafés or in the dead of night … The story of how I wrote Harry Potter and the Philosopher’s Stone is written invisibly on every page, legible only to me. Sixteen years after it was published, the memories are as vivid as ever as I turn these pages.’”