Locomotive superintendent William Barton Wright began by rebuilding a Jenkins tank with wheels in 1877 with side tanks and a trailing Webb radial axle, this being the first example of this type in the Britain. Further conversions ensued and a total of 18 were rebuilt by 1883. Ten new locomotives, the first taking the number 141, were ordered from Kitson in 1880 with driving wheels for freight traffic, these between designed to share components such as boilers, wheels, cylinders and motion as the existing 1876 engines. 14 of passenger variant of the design were supplied by Kitson in 1881 having driving wheels and a longer total wheelbase. A further 40 were delivered from Dübs & Company between 1882 and 1883.
