I always understood that Hitler did not really have an intention or a developed plan to invade the UK after the fall of France
I believe the high command thought the rout at Dunkirk had finished off the fighting spirit in Britain; Halifax would have his way, we would keep the Empire and Germany would have greater Europe.
Imagine their surprise when belligerent bugger Winston didn't play their game!
Interesting, looks like things on the German side could have started around 1937
They were; in terms of offensive RADAR they were ahead of the British. That was the flaw in the blitzkrieg plan - everything was geared up for the offensive; none of their edquipment was suitable for dull area monitoring.