The No. 4 Mk. III was the final, and crudest, form of the No. 4 spike bayonet. The socket is fabricated by welding together seven sheet steel stampings, eliminating the socket forging process altogether. Even the spring plunger is a stamping. 196,200 were produced, all by Joseph Lucas Ltd., Chester Street, Birmingham. The No. 4 Mk. III was declared obsolete in 1946