Lend/lease only began in March 1941. This is months after the BoB had ended.
Much is made of American shipments of 100 octane fuel, but.....
Consumption of Aviation Spirit
The following figures are for the Air Minstry and are the Average Monthly Consumption
September – November 1939 16,000 tons
Dec 1939 – February 1940 14,000 tons
March 1940 – May 1940 23,000 tons
June 1940 – August 1940 10,000 tons (100 Oct) 26,000 tons (87 Oct)
Sept 1940 – November 1940 15,000 tons (100 Oct) 18,000 tons (87 Oct)
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)
source:
http://www.ww2aircraft.net/forum/avi...2-a-20108.html
This is well researched with documentation.