Later the A type Overdrive was to be fitted to the entire range of TR cars. Famous marques including Jaguar, Aston Martin, Ferrari, Austin Healey, Jensen, Bristol, AC and Armstrong Siddeley were amongst the manufacturers to incorporate the overdrive unit into their engine systems. The first unit to be created was the ‘A’ type Overdrive, this was fitted to many sports cars during the 1950’s. The Overdrive Unit was a result of a chance meeting the year before, between Ken Walker, Production Engineer at Laycock Engineering Limited, and Captain Edgar de Normanville, a Transmission Designer. The Laycock de Normanville Overdrive Unit was first introduced to the Motor Industry in October 1948, when it was fitted to a Standard Vanguard.
