indeed they were known as the "County Tanks". These were then developed into a 2-6-2T design, being produced as the 3100 class in 1903 and the 3150 class three years later. Smaller 2-6-2Ts, the 4400 class were introduced in 1904 and were succeeded by the slightly larger 4500 class in 1906. Two very different freight tank locomotive types appeared in 1910. The 4200 class was a tank version of the 2800 class, but a demand for small locomotives for working on dock and branch lines was met by the 1361 class, a new design based on the old Cornwall Minerals Railway 0-6-0ST design but using as many of Churchward's standard parts as possible. Other innovations during Churchward's office included the introduction of self-propelled Steam Rail Motors for suburban and light branch line passenger trains. From 1915 his post was renamed that of the 'Chief Mechanical Engineer'. He also remodelled Swindon Works, building the boiler-erecting shops and the first static locomotive-testing plant in the United Kingdom. 101 Class 0-4-0T (oil burning): 101 The Great Bear (4-6-2): 111 1361 Class (0-6-0 ST): 1361–1365 County Tank Class (4-4-2T): 2221–2250 2800 Class (2-8-0): 2800–2883 Saint Class (4-6-0): 2900–2955, 2971-2990, 2998 3100 Class (2-6-2 T): 31xx (later 51xx) 3150 Class (2-6-2 T): 3150–3190 City Class (4-4-0): 3700–3719 County Class (4-4-0): 3800–3839 Star Class (4-6-0): 4000–4072 4200 Class (2-8-0 T): 4200–4299, 5200–5204 4300 Class (2-6-0): 4300-4399, 5300-5399, 6300-6399, 7300-7321, 8300-8399, 9300-9320 4400 Class (2-6-2 T): 4400–4410 4500 Class (2-6-2 T): 4500–4574 4600 Class (4-4-2 T): 4600 4700 Class (2-8-0): 4700–4708 Steam railmotors Petrol-electric railcar Charles Collett (1922-1941) Charles Collett became the Chief Mechanical Engineer in 1921. Almost straight away he had to take on all the locomotives of myriad types from the railways absorbed in 1922 and 1923. Many of these were 'Swindonised', that is they were rebuilt using standard GWR parts. He also set about designing many new types to replace the older examples. Many of the most familiar GWR tank locomotive classes were designed during this period: the 1400 class for small branch lines and auto trains; the 4575 class (a development of the 4500 class with larger tanks) and the large 6100 class 2-6-2Ts; the massive 7200 class of rebuilt 4200 class 2-8-2Ts; and the iconic pannier tanks of the 5700 class, the first of which appeared in 1929. Collett further developed the 4-6-0 type as the ideal GWR express locomotive, extending the