Coming to the attention of Lotus founder Colin Chapman, Walker was handed his Formula One debut at the 1971 Dutch Grand Prix to drive the Lotus 56B, powered by a Pratt & Whitney turbine engine.
Chamando á atención do fundador de Lotus, Colin Chapman, Walker fixo o seu debut na Fórmula Un no Gran Premio dos Países Baixos de 1971 pilotando o Lotus 56B, impulsado por un motor de turbina Pratt & Whitney.