Gethin made his debut in F1 for McLaren at the 1970 Dutch Grand Prix, replacing the team's founder, Bruce McLaren, who had been killed at the Goodwood Circuit earlier in the month.
Gethin debutou na F1 con McLaren no Gran Premio dos Países Baixos de 1970, en substitución do fundador do equipo, Bruce McLaren, que morrera no Circuíto de Goodwood a principios de mes.