The Duke of Sussex's explosive biography sold 64,148 copies in its first week, whereas Barefoot Kids, by Scott 'The Barefoot Investor' Pape, sold almost double that amount at 128,641 copies, Nielsen Bookscan figures show.

'Who'd have thought decent financial advice would outperform frostbitten todgers?' a publishing source told The Daily Telegraph, referring to one of the more notorious tales from Harry's book.