"The celebrations culminate on 25 June when the Queen holds a children's tea party at Buckingham Palace attended by children's characters including Postman Pat, Paddington Bear, Bob the Builder, Thomas the Tank Engine, the White Rabbit and Mary Poppins. Two thousand children between four and 14 will be invited, their names chosen from a ballot, with the winners meeting Harry Potter author JK Rowling. There are rumours the Queen will make her 'stage debut' in an entertainment also featuring supermodel Sophie Dahl and Harry Potter stars Daniel Radcliffe and Emma Watson. The BBC will broadcast the event live."