When I motored seriously I had 3 sets of full harness. Firstly a very crude and cumbersome type, IIRC of Britax origin. Then as my ambitions became more serious an Irving set.
Danny you have a suspicious mind!
No doubt they were rather expensive to buy. But over on the far side of your field the Fire Section..........
Yes they were more expensive but not that much more than Britax. The straps were softer than anything I have experienced before or since and release so simply, 1 finger flip. They had a 3 point anchorage which made life inconvenient for a back seat passenger and a single tensioner. For my navigator I had a conventional three point belt but still Irving, same release, same soft webbing and easy tensioner.
When I got very serious it was back to Britax, (I think Irving had gone out of the car market) reasonable but coarser harness, 2 tensioners and a more complicated release. Also no longer inconvenient for a back seat passenger but impossible! Of course the advancing commercialisation of motorsport did mean discounts and bonuses. However the left hand seat kept its comfortable Irving.