Hundreds of screaming Potter fans queued outside the studios in Leavesden, near Watford in Herts, where all the multimillion pound-grossing films based on JK Rowling's magical stories were shot.
Local boy Grint, who played Ron Weasley, said: "This is the most glamorous I've ever seen Watford."
More top news
Labour leader tells May Day rally his party 'stand absolutely against racism in any form'.
After a largely fine and sunny start to the day a bank of cloud and rain is currently making its way southeastwards across Britain.
A woman gave birth to a baby boy on the hard shoulder of the M42 after getting stuck in traffic.