The book outlines a critical history of the British Communist Party and the Left. It focuses on the relations of the CP with the wider labour movement. British Marxism failed to carry on a dialogue with mass labour organisations. Unions did not desert the Labour Party because there was no credible left alternative in the period examined. Why was this so? What was on offer? The authors conclude that more often than not, and especially in times of crisis and radicalisation, the Communist Party stood on the right of the labour movement, they sketch a history of Trotskyism developing out of these critical perspectives.