Four similar classes of this type were built between 1903 and 1949, being known as 31xx, 51xx, 61xx and 81xx. They began with No. 3100, introduced as one of the new Churchward standard designs, in 1903. Building of the type continued under Churchward's successor Collett, sometimes incorporating parts from the earlier engines as these were withdrawn from service.
Apart from London, with only one example, the 51xx class engines were allocated to many depots throughout the Great Western system. They often became the mainstay of the suburban services, besides being employed to bank heavy trains uphill in Somerset, Devon and through the Severn Tunnel. They lasted until replaced by dieselization from 1957 onwards.
4144 was built at Swindon in September 1946 and, having spent time as the Severn Tunnel banker, was withdrawn from Severn Tunnel Junction depot in March 1965. The locomotive was sent to Woodham Bros. of Barry for cutting up but survived until it was bought jointly by the Society and one of its members in 1974.
The rebuild was completed in 1997 and 4144 was used on the ‘Steam on the Met’ in 1998.
The locomotive had its boiler removed for overhaul in August 2010 and officially re-entered service on 2 May 2015. As well as use at Didcot the locomotive visited the Severn Valley Railway in 2019 and the Kent and East Sussex Railway in 2020.