Prince William dreamed of becoming a policeman when he was younger, the heir to the British throne has admitted - while also revealing how he came to get a "Harry Potter scar" on his forehead.

The 26-year-old royal opened up in an interview for a children's television program, answering questions from a young cancer patient at London's renowned Royal Marsden hospital.

Asked what he wanted to do as a child, he said: "A long time ago I wanted to be a policeman, when I was younger. I soon learnt that probably wasn't a good idea.