I suspect a lot of the canley Classic article is when the electric fans had a big cowl which although directs the air through the fan when running, effectively restricts the air when not. Or the brackerery shields the rad particularly when the rad is the smaller type and is marginal at best.
I fitted a full width rad to my spitfire and has run lovely since. Temperature sits smack in the middle of the gauge. It used to overcool which although it had a thermostat fitted I suspect it was knackered or the wrong temperature range.