In general, German bombers were likely to get through to their targets without too much difficulty. It was to be some months before an effective night fighter force would be ready, and anti-aircraft defences only became adequate after the Blitz was over, so ruses were created to lure German bombers away from their targets. Throughout 1940, dummy airfields were prepared, good enough to stand up to skilled observation. A number[clarification needed] of bombs fell on these diversionary ("Starfish") targets.
What kind of airfields were prepared to stand up to skilled observers?  (If the question is unanswerable, say "unanswerable")
dummy