To complicate it further: According to War over Holland: 'The planes took off from Bircham at 1950 hours [Dutch time] and (...) returned at 2250 hours.'
Dutch time in 1940 was somewhere in between German and English time and different from the Belgian and French time. Since according to War over Holland the planes were for two hours in the air, the bombardment must have taken place at approx. 21.50 hrs (Dutch time). Which doesn't quite fit with the 22.10 hrs (English time?) of Peter. Or does he use Dutch time as well?
For the crash location: Herkingen polder and beach Overflakkee could be the same. Hope this direct link to Herkingen (on Goeree-Overflakkee isle) works:
Herkingen
Regards,
Bart