Prince Harry's "Spare" became the UK's fastest selling non-fiction book ever, its publisher said on Tuesday, after days of TV interviews, leaks, and a mistaken early release of the memoir containing intimate revelations about the British royal family. Harry's book has garnered attention around the world with its disclosures about his personal struggles and its accusations about other royals, including his father King Charles, stepmother Camilla and elder brother Prince William. Citing British sales figures, the publisher said it had sold 400,000 copies so far across hardback, e-book and audio formats.