the intercity 125 is the brand name of british rail's high speed train (hst) fleet. the intercity 125 train is made up of two locomotives, one at each end of a fixed formation of carriages, and is capable of 125 mph in regular service. british rail initially used the fleet on the great western main line, on the east coast main line, on the cross country route and latterly on the midland main line, serving destinations such as london, bristol, edinburgh, as far south as penzance and as far north as aberdeen and inverness. the intercity 125 took the world record for the fastest diesel-powered train, when it was recorded at an absolute maximum speed of during 1987. from 2017, most have been replaced by the british rail class 800.