Originally Posted by
QDMQDMQDM
Brown says it was 5 miles, shortened to 3 miles after the war.
A look at
This Link confirms BEagle's figure of 3 miles in 1943, shortened to 2 miles during 1945 - 46.
What isn't clear is whether this refers to nautical or statute miles, which would obviously make a considerable difference to the runway lengths in feet, although not enough to explain WB's figures.