 Beamish founded in 1914 the British Citizen Movement (BCM), an anti-German organisation which campaigned for the purchase of British products to support the war effort; he then became involved with the Consumers' Alliance, which advocated for the exclusion of Germans from business in South Africa.During the First World War, Beamish served in the Natal Regiment of South African Infantry.Thereafter, he moved back to England, convinced from his experiences in Africa of having "discovered" a world-wide Jewish conspiracy theory.