May Day is the traditional day for workers’ celebrations. These events have often been used to promote peace and internationalism. The May Day rally in Hyde Park in 1936 coincided with a large demonstration organised by the Communist Party of Great Britain. Aneurin Bevan – seen addressing the crowd in the photograph - was elected as the Labour MP for Ebbw Vale in 1929. He was initially a critic of British rearmament, speaking against it at the Labour Party conference in 1937. As Minister of Health in the post-war Attlee government, he played a crucial role in the establishment of the National Health Service.