Mark 3 Coach

The British Rail Mark 3 is a type of passenger carriage developed in response to growing competition from airlines and the car in the 1960s. A variant of the Mark 3 became the rolling stock for the High Speed Train (HST). The Mark 3s were built by BREL. They were air-conditioned throughout, something modern that wasn't used in Mark 1s or Mark 2s.undefined Originally conceived as locomotive-hauled coaching stock, the first coaches built were for the prototype HST in 1972. Production coaches entered service between 1975 and 1988, and multiple-unit designs based on the Mark 3 bodyshell continued to be built until the early 1990s. The Mark 3 and its derivatives are widely recognised as a safe and reliable design, and most of the surviving fleet is still in revenue service on the British railway network in 2018.