The next conversions were from Class A, and were rebuilt as simples, retaining the 0-8-0 wheel arrangement: two inside cylinders were fitted in place of the original centre cylinder, and the outside cylinders were removed. Between November 1904 and March 1906, 15 locomotives were converted, using cylinders of diameter; these retained their original boilers and were later designated Class C. Between March 1906 and March 1909, 62 locomotives were converted, these were also given cylinders but were provided with larger ("Experiment" class) boilers and were later designated Class D. In December 1906 the original Webb 0-8-0, no. 2524 (which had never been a compound) was also given a large boiler and joined Class D. From March 1909 until September 1912, the last 34 conversions from Class A again retained their original boilers, but the new cylinders were of diameter; they were later designated Class C1.