JK Rowling has sent Harry Potter fans into a frenzy by revealing a short story about a grown-up Potter online today (July 8).

The 1,500-word piece released on her website Pottermore.com centres on a now 34-year-old Harry Potter with greying hair attending the Quidditch World Cup 2014.

Rowling has also been writing other pieces on the tournament for Pottermore to coincide with the World Cup in Brazil.