Stepney was built by Brighton Works in 1875 as an LB&SCR A1 class engine, and was rebuilt into an A1X in 1912. During his final working years, Stepney worked on the Hayling Island branch line, until he was taken out of service in 1960 and placed on an out-of-use siding. He was bought by the Bluebell Railway Preservation Society and arrived on the railway on 17th May, making him the first standard gauge steam locomotive in the United Kingdom to be preserved.
Stepney is painted in the LB&SCR goldenrod livery, formally known as "Stroudley's Improved Engine Green", with green, red, white and black lining. His name is painted on his side tanks and the number "55" is painted on the sides of his bunker, both in white. The real Stepney has a brass funnel top and brass numberplates with a blue ground. He carries two builder's plates on the sides of his splashers.