Rowling, 51, has pleaded with fans not to buy the “extremely valuable” work which was stolen along with various items of jewellery during a burglary in Kings Heath, Birmingham.
The 800-word story, written on both sides of an A5 card, sold for £25,000 at a charity auction at Sotheby’s in 2008.
Rowling urged fans not to buy the rare manuscript, tweeting: “PLEASE DON’T BUY THIS IF YOU’RE OFFERED IT. Originally auctioned for @englishpen, the owner supported writers’ freedoms by bidding for it.”
West Midlands Police have issued a plea for information in the hope that “the appeal goes far and wide among Harry Potter fans throughout the world”.
Rowling shared their tweet, which read: “We are asking #HarryPotter fans to help share our appeal after a rare Harry Potter prequel by @jk_rowling was stolen.
“The story, penned personally by @jk_rowling over 2 sides of an A5 postcard is extremely valuable & stolen during a burglary in #KingsHeath.”
The prequel was among several works donated by authors, including Sebastian Faulks and Doris Lessing, to an auction held in 2008 to raise funds for English PEN, which promotes understanding through literature, and Dyslexia Action.
The story is reportedly set three years before Harry Potter’s birth, and features the schoolboy wizard’s father, James Potter, and godfather, Sirius Black, when they were teenagers.
They are confronted by two “muggle” policemen after a high-speed motorbike chase but manage to escape on broomsticks.
Anyone who knows the whereabouts of the postcard, or who has information about the break-in, is urged to contact West Midlands Police on 101 or Crimestoppers anonymously on 0800 555 111.