I remember pool petrol even though I wasn't old enough to enjoy it, the premium grades came in mid-50s I think: remember Esso Golden with its brilliant Tiger in the Tank campaign?
Pool was the 'utility' fuel of wartime and used for pretty well everything except aviation. It was about 70 octane while the avgas grades were leaded up to 100/130 octane, though the low-compression Gipsy Major (TM, Magister etc) would run on it.
I was mightily impressed when shown over a DB601 as used in many German aircraft. It had a small lever which retarded the ignition to enable the use of low-octane motor fuel albeit with reduced power. I've read that the development of fuels was as important as engine development in the quest for more horsepower.