Bellerophon was one of six almost identical locomotives built for the Haydock Collieries between 1868 and 1887, Bellerophon herself being completed in 1874.

Unusually for the time the locomotives had outside motion and a further revolutionary aspect was the use of piston valves, nearly two decades before this type of the valve gear is generally recognised as being in use. Bellerophon, being the only survivor of the class, is therefore unique, not only for having Stephenson/Gooch valve gear but because she is the last of the only six engines ever built at the Haydock Foundry.

The Haydock Collieries and Foundry covered a large area and their products, as well as some of their raw materials, had to be moved by rail. For this reason, the sites were all interconnected by 60 miles of private railways and links to the London & North Western Railway and the Liverpool & Manchester Railway. Locomotives were needed which could handle heavy trains over quite severe gradients and which would be hard-working, robust and reliable.

Josiah Evans, one of the family who owned the complex, was a competent engineer, and he was responsible for organizing the foundry to make it capable of supplying the needs of the Colliery and rail complex. In doing so he conceived the idea for Bellerophon and her sisters to fulfil that need.

Bellerophon and the others (named Makerfield, Parr, Golborne, Hercules and Amazon) worked faithfully for many years. Amazon was the first to go, in 1935, with the others being taken into ownership by the National Coal Board
upon nationalization. By 1964 Bellerophon was the only survivor and in that year was sent for scrapping. At the last minute, she was rescued and arrived on the Keighley & Worth Valley Railway.

In 1981 Bellerophon was purchased by Vintage Carriages Trust from the KWVR for £1 and restoration work commenced.

As work progressed it was found that the locomotive was quite literally worn out, but a small and dedicated restoration team rose to the challenge and four years later were rewarded with the first steaming since 1964. Since then Bellerophon has become something of a celebrity and is often in demand by other railway groups – including a very successful visit to Belgium and to The Netherlands. At present, the locomotive is on loan to the Foxfield Railway.