Across the four corners of Britain, on stages and behind closed doors, hundreds of communities, friends, neighbours and colleagues are getting together to experience the power, joy and togetherness singing in a choir brings.As the nation prepares for the coronation of King Charles III, a very special choir is given the once-in-a-lifetime chance to sing their hearts out for the King and Queen Consort and the millions watching around the world at the coronation concert in Windsor Castle. The choir is made up of singing groups of all shapes and sizes; ordinary people who are passionate about the power of song to bring together their communities.Ready to roll up their sleeves and put the choirs through their paces are celebrity mentors Gareth Malone, Motsi Mabuse, Amanda Holden and Rose Ayling-Ellis.