The Canadian-American Challenge Cup (Can-Am) of 1966 to 1974 earned iconic status among motorsport enthusiasts for basically having no rules governing the design of its cars.
The FIA-sanctioned Group 7 regulations to which it was run dictated only that cars had enclosed bodywork and space for two people.
It is not as widely remembered, however, that Europe had its own (albeit much lower-profile) Group 7 championship, named Interserie, from 1970 to 1976.
In May 1972, we reported as it held its first race at Silverstone. Eighteen ‘big bangers’ were entered, although sadly none by British Can-Am leaders Lola and McLaren, the former’s new car not ready and the latter busy with the Indy 500.
The front row was locked out by Porsche 917s, Bosch-backed Willi Kauhsen pipping AAW’s 1971 champion Leo Kinnunen, both with works support.
The Finn was leading comfortably from the German on lap 28 of the first 35-lap race, then suddenly both got punctures and it started to rain.
Having fitted slicks, Kinnunen then lost 45sec in just five laps to the JCB-run Ferrari of Willie Green.
No such drama befell the AAW man in the second race, so he took the overall victory ahead of Green.