The parents of murdered Harry Potter actor Robert Knox are calling for a mandatory six-month sentence for anyone caught carrying a knife.

Colin and Sally Knox have met Gordon Brown, the Home Secretary Alan Johnson and other families of knife crime victims in Downing Street.

Robert was 18 when he was stabbed outside a bar in Sidcup in May last year.

He lived in Maidstone Road, between Swanley and Foots Cray.