Charlie Gilmour was sent to Wandsworth Prison for violent disorder following a tuition fees protest the previous year. That led to his father's interaction with The Liberty Choir, which arranges sessions behind bars between inmates and members of the South London Choir, and continues them when sentences come to an end.

Confirmed that seven former prisoners lent their voices to Rattle That Lock, Gilmour tells the BBC: "It's wonderful - they have a place outside prison where they feel part of of the community."