Can anything be done? The statistics for people killed or injured by knives in Britain are horrifying. Idris Elba hopes his new campaign will reduce them dramatically.
The London rapper calling time on knife crime
Disturbing reality: Half of teenagers in England and Wales have witnessed or been victims of violence, study reveals. Glossary
Oblivious - Completely unaware or uninterested in what is happening around you.
Idris Elba - An English actor, rapper and singer, born in London in 1972.
Zombie knives - Bladed weapons inspired by zombie films.
MPs - Members of Parliament. MPs are elected to represent people in 650 different geographical areas.