Design of the car broadly followed Broadley's experience in the Formula Junior category, with a steel spaceframe chassis braced by bulkheads in front and behind the driver.

Surtees took the car's first victory in the 2000 Guineas race at Mallory Park in the middle of the season, but excess chassis flex impeded his Championship hopes.

With the uprated designs results continued to trickle in, but a lack of development funding stunted the cars competitive growth, and by the end of the season both the Mk4 and 4A were completely outclassed.

Two such-equipped Mk4 cars were shipped to New Zealand and Australia for their respective Grands Prix in early 1963, where regular driver Surtees was partnered by up-and-coming South African Tony Maggs.

One Mk4 was sold to privateer Bob Anderson who entered the car into many Championship and non-Championship races, winning the 1963 Rome Grand Prix.