The 'Collett Goods' or 'Baby Castle' (as it was sometimes affectionately called by its drivers) was first introduced to the Bachmann Branchline range in 1998 and is not the model previously made for Palitoy's Mainline range. It is based on the GWR standard 0-6-0 goods locomotive, introduced by Collett in 1930.

Following the Grouping of 1923, when the GWR absorbed a number of small railway companies in Wales, it found itself with a number of lightly constructed lines that required light goods locomotives. No 0-6-0 tender locomotive had been built by the GWR for some time, as the emphasis had been on heavy freight locomotives. The existing Dean 0-6-0s were getting old and so a new class of light 0-6-0 tender engines was required. The building of Collett's standard 0-6-0 class started in 1930 and continued in batches until 1948. Swindon built them and the class finally totalled 120.

They were initially used for pick-up goods trains but, in BR days, they were acknowledged as mixed traffic engines, finding themselves on both cross-country routes and branch lines and pulling passengers as well as freight.