A first edition copy of Harry Potter and the Philosopher's Stone, with author JK Rowling's notes and original illustrations, was sold for £150,000 at auction in London, The Guardian reported.

The book, which was auctioned by Sotheby's at a charity sale in aid of the English Pen writers' association, was purchased by an anonymous bidder by telephone.

The annotations by Rowling include comments on the process of writing and a section from an early draft of the novel, along with a number of illustrations drawn by her and a note on how she came to invent Quidditch, a sport played by characters in the books.

She and others had been asked to "scribble second thoughts, marginalia or drawings" on a first edition copy of one of their books for the event, which raised £439,200 in total.

A copy of Roald Dahl's bestselling children's book Matilda, containing new drawings by illustrator Quentin Blake, fetched £30,000, while an annotated copy of Kazuo Ishiguro's novel The Remains of the Day went for £18,000.