Back in the mid-1990s JK Rowling’s Harry Potter and the Philosopher’s Stone was rejected by no less than 12 publishers before being accepted by Bloomsbury.

The book, which became the fourth best-selling novel of all time, had its original cover art painted by 23-year-old Thomas Taylor, who was fresh out of art school.

And now his original watercolour work of Harry standing in front of the Hogwarts Express is going up for auction.

According to Sotheby’s New York, the piece is expected to…