Powlesland and Mason were a company that provided steam locomotives and crews for shunting within Swansea Docks. They utilised a fleet of nine 0-4-0ST locomotives, which had been built between 1874 and 1916, for duties within the docks.
GWR 921 (P&M no 6) was built in 1906 by Brush and worked at Swansea Harbour. In 1924 the GWR took control of shunting operations at Swansea Docks and thus the locomotive passed into GWR ownership. It then managed to acquire a Swindon-style safety valve bonnet which it still retains.
In September 1928 the locomotive was sold to Berry Wiggins & Co Ltd who were based in Kingsnorth in Kent.
The locomotive was withdrawn in 1964 and presented to Leicester Museum of Technology in 1968.
