The Duke of Cambridge has revealed the shock of his mother's death is still with him, twenty years after she was killed in a car crash in Paris.

Prince William was speaking in a BBC documentary which follows a group of people affected by mental health problems, who are training to run the London Marathon on Sunday.

The two-part series, Mind Over Marathon, starts on BBC One at 21:00 BST on Thursday 20 April, as part of a Minds Matter series of programming about mental health issues.