Known collectively as Light Pacifics and nicknamed ‘Spam Cans’, the West Country and Battle of Britain classes were designed as air-smoothed 4-6-2 Pacific locomotives by the Southern Railway’s Chief Mechanical Engineer, Oliver Bulleid. Designed to be lighter in weight than the similar Merchant Navy class, they could be used on a wider variety of routes, including the Kent coast and South West of England. The class were constructed using new working practices and techniques in locomotive construction, this included all-steel welded boilers and the use of steel fireboxes and was due in no small part to the need to ease construction during the wartime and post-war austerity years.
The Light Pacific’s beginnings came from Southern Railway’s order for twenty locomotives in 1941, at that time of an unspecified design, to replace the ageing T9 Class in the West Country. With Brighton Works’ spare capacity being taken up with the manufacture of wartime goods engines, it was to be 1943 before Bulleid proposed a mixed traffic locomotive design, based on his existing Merchant Navy class, but shorter, lighter and with a smaller tender. Building of the new locomotives commenced in 1944 and the first locomotive of the West Country class, 21C101 Exeter, entered service in May 1945, with the last of the first batch of twenty being completed by December that year.