At the start of the War the Vickers factory at Erith was responsible for the design and manufacture of the Vickers machine gun; a replacement of the now obsolescent Maxim machine gun. With orders for 1792 machine guns in the first eight weeks of the War, followed by a French order for 50 guns a week, Erith was unable to cope with increasing demands from the armed services. Crayford was laid out to manufacture machine guns in addition to small calibre artillery pieces, breech mechanisms, fuse setters, predictors for anti-aircraft guns, and fire control and directors for naval guns, but due to labour shortages, disputes, and lack of co-operation between the two factories, production of machine guns had only reached 40 a week by the end of 1915. In one dispute over 500 workers, many of whom were Belgian refugees, stopped work for five days over non-payment of a war bonus.
Things had improved by the end of 1916 and the production of machine guns had reached 321 a week. By the end of 1918 the two factories were producing 1,250 guns a week, 30% of the UK production. Discipline in the works was strict, workers were not allowed to make tea or other beverages and written permission was required to leave one’s workplace. Working hours were long, weekdays 7.30am to 5.00pm with overtime to 7.30pm, plus Saturday and Sunday mornings.