In 1940 Sheffield was a city of about 560,000 people and contained many heavy industries, primarily centred around steel and armaments. The Vickers works was host at the time to the only drop hammer in the country, made in Germany by Beche, capable of forging crankshafts for the Rolls Royce Merlin engine which powered the Supermarine Spitfire fighter plane and later in the war the Avro Lancaster bomber. The hammer itself weighed 15 tons and was housed in a 200 ton mounting. It was manned by 16 men working in two shifts. The hammer produced 168 forgings a day which was one of the three operations necessary to make a crankshaft. Hadfields steelworks was also the only place in the UK at that time where 18 inch armour piercing shells were made. Most of the factories were located in the East en