The British press gave the F100 a far from warm welcome, fearing that the class would rival the popular Clubmans.

But when Nick Cole became the faster driver in a BMC powered Nerus Silhouette, Allen quickly changed engines.

The series' final race at Brands Hatch on December 27, 1971 proved to be a farce as only one driver made the grid.

The Royale RP4, Merlyn MK 16, Aldon F100 and the Nerus Silhouette are examples of Formula F100 cars.

Despite the 300cc smaller engine, the cars were only slightly slower than Formula Ford due to their superior aerodynamics.