6 choirs and vocal groups of all different sizes and genres battle it out for a place in the grand final including an all-female barbershop group.

6 more groups compete for a place in the final including a group of childhood friends from Loch Lomond and an acappella YouTube sensation. With guest judge Chaka Khan.

Among the 6 groups competing in the third heat are a Polish jazz vocal group, a Welsh choir and a gospel choir from London.

Seal is the guest judge as 6 more groups compete, including an all-female country group, and a gospel choir from Portsmouth University.

Six more vocal groups from musical genres as diverse as classical, barbershop and pop compete in a series of musical challenges.

The 5 heat winners and one wild-card compete in the live final of the singing contest for choirs and vocal groups. Hosted by Mel Giedroyc.