Bachmann Branchline 31-828 Class 43xx 2-6-0 Mogul 5370 in BR lined black with early emblem

By the beginning of the 20th century the GWR had realised that its ageing fleet of four-coupled tender engines of 2-4-0 and 4-4-0 arrangement could no longer provide the necessary operational requirements of the railway. H. Holcroft, a senior engineer under Churchward, the railway's Locomotive Superintendent, toured North America to research replacement designs. He was most impressed with their 2-6-0 'Mogul' locomotives. On his return to Swindon he was instructed to design a similar locomotive utilising as many standard parts as possible. The outcome of this design was a tendered version of the Class 3150 2-6-2T, incorporating 5ft 8in wheels, outside cylinders and a 3500 gallon tender, designated the Class 4300 locomotive. An initial order for twenty locomotives was placed, entering service in 1911, the enginer quickly gained a reputation for excellent performance hauling both passenger and freight trains. A second batch of locomotives produced in 1913 had lengthened rear frames to accommodate included cab side windows, and a screw reverser replacing the original lever type. Production ended in 1932 with 342 locomotives completed, carrying series numbering of 4300, 5300, 6300, 7300 and 9300.
-á The original GWR locomotives were painted in a lined green livery, later to be repainted in an unlined green livery. BR livery was plain black, except for a few locomotives which received lined black. In 1956, plain green was applied, but this was soon revised the following year in favour of fully lined out GWR style livery. The last remaining Class 43xx was removed from service in 1964.