Joseph Tomlinson developed a goods locomotive with the wheel arrangement 0-6-0 and double frames for the Taff Vale. A total of 44 were built by Taff Vale's own workshops in Cardiff and by several other manufacturers.
Under Tom Hurry Riches, four of these locomotives were rebuilt to passenger tank locomotives with the wheel arrangement 0-4-4T. This conversion resulted from the elimination of the third driving axle, the installation of coal and water tanks and the addition of a trailing bogie.