The centenary of the outbreak of the first world war has already been marked by two outstanding albums – Robb Johnson's Gentle Men and the Show of Hands collaboration with Jim Carter and Imelda Staunton – and now comes a double album from Barry Coope, Jim Boyes and Lester Simpson, a trio of exhilarating a cappella singers who have done more than most to express the horrors of the conflict in their songs, and have been involved in a series of war-related projects, including concerts on former battlefields. The 50 tracks here include new and old recordings of wartime songs and their own compositions, with occasional piano work from Belinda O'Hooley and vocals from June Tabor on the atmospheric Shule Agra. But they are equally powerful on their own, with magnificent, stirring harmony work on the cheerfully bitter Hanging on the Old Barbed Wire or Jim Boyes' bleak lament, Hill 60.