Britain's stopgap diesel train outlived the futuristic project it was meant to cover
In 1970 British Rail needed something quick while its tilting Advanced Passenger Train stalled. The fallback was a diesel with an engine at each end, and a designer hired only to choose its paint secretly reshaped its nose. The InterCity 125 became one of the most successful trains ever to run in Britain.
Governments of the era would not pay for dedicated high-speed lines, so the railway had to go faster on existing track. When the board concluded in 1970 that the APT would not carry passengers until well into the next decade, chief engineer Terry Miller pushed for a high-speed diesel. The formula was simple: Mark 3 coaches sandwiched between two streamlined power cars, each carrying a Paxman Valenta engine of 2,250 horsepower, chosen because it was light for its output. The earlier Blue Pullman sets had tried the double-ended idea without commercial success, but they showed it could work.
Stopping mattered as much as speed. To halt from 125 mph within existing signal spacing, the train needed powerful disc brakes instead of traditional clasp brakes. A prototype was finished in August 1972, and on 6 June 1973, on the so-called racing stretch from York to Darlington, a slimmed-down set touched 131 mph. Before its introduction, British diesel trains had been capped at 100 mph.
Kenneth Grange was asked only to design the livery. On his own initiative, and without telling anyone, he tested a new wedge-shaped nose in a wind tunnel with an aerodynamicist. His wider cab also solved a labour dispute: the drivers' union ASLEF had refused to run the prototype in service because there was no seat for a second crew member beside the driver.
Production power cars came from Crewe Works and coaches from Derby Litchurch Lane, with the first, 43002, delivered in late 1975. Partial service at 125 mph started from London Paddington on 4 October 1976. By 1982, 95 sets had been built. Lighter axle loads let them outpace older trains even on twisty routes such as Edinburgh to Aberdeen, and the design inspired Australia's XPT, which began running in New South Wales in 1982.
Source: InterCity 125
