Visit www.wearelumos.org for more information about the charity. The sale of English literature, history, children’s books and illustrations (as well as the charm bracelet) will take place at Sotheby’s, 34–35 New Bond Street, London W1, on 10 December.

J.K. Rowling: On the day that the seventh Harry Potter book was to be released, my editor, Emma, and the head of Bloomsbury children’s books, Sarah, met me in London and gave me a small package to open. Inside was what would become (aside from my wedding ring) my most treasured piece of jewellery: a bracelet covered in gold and silver charms from the books. There was a tiny Golden Snitch, a silver Ford Anglia, a Pensieve and a stag Patronus. There was even a Philosopher’s Stone in the form of an uncut garnet.

Unfortunately, my personal Philosopher’s Stone did not last the night. Somewhere during an eight-hour signing session it must have broken against the table, because when I got home the following morning it was gone. Vaguely, in my tiredness, it seemed a portent. The series was finished and it was time to move on.