After winning another hat-trick of championships between 1965 and 1967, Marsh sold his car and left motorsport to concentrate on his engineering and farming interests, but in 1986 he returned at the wheel of the March-based Rovercraft.
Logo de gañar outro hat-trick de campionatos entre 1965 e 1967, Marsh vendeu o seu coche e abandonou o motor para concentrarse nos seus intereses de enxeñería e agricultura, pero en 1986 volveu ao volante do Rovercraft baseado no March.