The Briham PRH 5 was a further development of the Mk 4 design that was commissioned to meet new Formula 4 regulations. The chassis was modified to accommodate the 850cc Hillman Imp engine and transaxle.

The modifications to the Mk 4 design, however, stretched the chassis design to beyond its capability.

The prototype car was sold, later modified and brought up to competition standard but under a different marque.