InterCity 125 was the brand name of British Rail's diesel-powered High Speed Train (HST) fleet,
which was built from 1975 to 1982 and was introduced in 1976. An InterCity 125 train is made up of two Class 43 power cars, one at each end of a fixed formation of Mark 3 carriages (the number of carriages varies by operator). The train operates at speeds of up to 125 mph in regular service, and has an absolute maximum speed of 148 mph, making it the fastest diesel-powered train in the world, a record it has held from its introduction to the present day. Initially the sets were classified as Classes 253 and 254. A variant of the power cars operates in Australia as part of the XPT.