The Napier-Railton Special was commissioned by John Cobb with the object of setting lap records at the Brooklands race track in the UK, as well as establishing endurance records up to 24 hours. The goal was sustained speeds in excess of 150 mph (241 km/h) which was unheard of at that time.

Cobb had made a small fortune as a fur broker which, in the 1920s, allowed him to pursue his passion of auto racing. In the early thirties, Tim Birkin, Cobb´s great rival, was beating him with his supercharged Bentley Special. A more powerful car was needed. The task was given to Thomson & Taylor and, more specifically, Reid Railton their chief engineer.

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Their starting point was the Napier Lion XIA aircraft engine, a compact, but very powerful, 12 cylinder 'W' design capable of delivering in excess of 500 bhp without supercharging.