Daniel Radcliffe, who plays the teen wizard, attended the red carpet bash at Universal Studio Resort in Orlando, Florida, along with the likes of Rupert Grint (Ron Weasley), Tom Felton (Draco Malfoy) and Michael Gambon (Dumbledore).

Author JK Rowling also turned up to greet fans and the cast stood on a stage waving their magic wands.

It is not know why Watson couldn't attend but the actress did visit the theme park last month.

For the grand opening of the theme park, which opens to the public tomorrow, an illuminated Hogwarts Castle was flooded with smoke.

The park features a Hogwarts Express and the city of Hogsmeade which true to the books has a Zonko's joke shop, post office Owl Post and sweet shop Honeydukes.