Pilots Operating Limitations, June 1940:
All out 5 minute Emergency rating as listed in June 1940:
If by June 1940, 30 squadrons were operating 100 Octane, then almost the entire force would need the +12lbs boost instructions instead of the 87 Octane. The Operating Notes would have reflected this and the 100 Octane limits would have been included.
That is a fact and how it works.