This locomotive was built by Sentinel in 1956 for Courtaulds Fibres at Great Coates in Grimsby.
Originally, the order required that the locomotive was able to have its boiler pressurised direct from the main steam supply in the factory itself to reduce the fire risk inside the works.
The locomotive was given the name William in memory of the Sir William Stanier.
The locomotive was employed hauling wagons’ carrying coal, caustic soda and other materials around the plant.
It was joined there by Sentinel Works No 9596.
9599 continued in regular service until 1978 when it duties were taken over by diesel shunting locomotives.
After being stored following the introduction of diesel locomotives both Sentinel locomotives were sold in the 1980s.
Originally 9599 went to Peak Rail where it was only used on a limited basis and was eventually put into store.
In 1994 it was bought by a private owner and moved to the Middleton Railway where it was restored to traffic.
In 1996 it was moved to the Battlefield Railway.
In March 2008 the locomotive moved to the Elsecar Heritage Railway where it was once again returned to steam.
In 2016 the locomotive was fitted with a new boiler.
It is currently operational on the Elsecar Heritage Railway where it runs as LMS 7165.