She answered as many questions as possible, revealing some fascinating stuff about the future of Harry Potter.

She said there will be more romance for the boy wizard in books 6 and 7 - and that if she was Harry she would "go and hide 'cause she knows what's coming".

JK even found time to answer a question from our Newsround competition winner, 11-year-old Stacey from Plymouth.

Stacey asked JK who she would be if she could take a polyjuice potion.

JK replied: "I'd like to be Tony Blair for an hour. I'd call a press conference and announce all the policies I'd like to implement."

Artemis Fowl

Newsround is continuing the World Book Day celebrations with its own webchat featuring Artemis Fowl author Eoin Colfer.