Len Deighton, in Fighter, claims that the Brits left a portable radar set behind at Dunkirk, and there was much consternation that it hadn't been destroyed. When the Germans discovered it, they were not at all interested, it was so far behind their stuff.
Len Deighton does a lot of research, but he's also a professional story-teller. Does anybody know what, if any, actuality lies behind this anecdote?