Pratchett's books have sold more than 23 million copies worldwide and are outsold in the UK only by JK Rowling's Harry Potter series.

BBC: Pratchett novels go to Hollywood

The novel topped several ebook charts ahead of its release due to high interest in JK Rowling's first novel for adults, following the success of her Harry Potter series.

BBC: JK Rowling's The Casual Vacancy ebook suffers glitches