From another forum:
Reserves Information
The following information are the reserve stocks of 100 Octane fuel during the BOB period
This information has come from the War Cabinet Oil Position Monthly report (a) that is available from the National Archives, as well as Gavin Baileys paper(b) and Wood and Dempster(c).
Stocks of 100 Octane
30th September 1939 153,000 tons(b)
27th February 1940 220,000 tons(b)
31st May 1940 294,000 tons(a)
11th July 1940 343,000 tons(b)
31st August 1940 404,000 tons(a)
10th October 1940 424,000 tons(c)
30th November 1940 440,000 tons(a)
Oh found this: from
http://www.flightglobal.com/pdfarchi...0-%202155.html "It fell to the
Shell Development Company in California to produce for the first time a commercially manufactured 100-octane gasoline
in 1935. It was 50/50 straight-run material with synthetic blending agents, plus 4.8 c.c. tetra-ethyl-lead per Imperial
gallon."