Enjoy a cuppa as your guardian looks over you with this wonderful Patronus Heat Change Mug. This Heat Change Mug features the phrase ‘Expecto Patronum’™ on its side, in electric blue writing on a dark black background when cold. And once you’ve poured in your favourite hot beverage and it warms up, Harry’s own stag Patronus appears from the darkness. This standard sized mug with heat changing decal is a fabulous gift for Harry Potter fans and is a great accompaniment to your next mid-Potter tea-break. First published in 1997, J.K. Rowling’s bestselling series of novels following the magical adventures of Harry Potter, Ron Weasley and Hermione Granger has since become a cultural phenomenon. A huge success in novel form, the world of witchcraft and wizardry was then given big screen treatment in 2001, launching one of the most successful blockbuster film franchises in cinema history. Harry Potter is instantly recognisable to millions of people across the world, and is hugely popular among fans of all ages. The Patronus Heat Change Mug is an officially licensed Harry Potter product.