[Marius]

Nevertheless I think the authors used relevant sources...
By the way, it is most propable the RAF lost much more aircraft crashed or forcelanded on England soil then only the 12 which completely failed to return - means crashed into the North Sea.

I don`t think there is something untrue done by above authors. More, the British point of view seems to be much problematic even now, 75 years after the battle.
I only wrote about the losses of Squadrons 9,37,38 & 149 passing Heligoland. But it is sure pilots of 2./ZG 76 (among others) attacked the second formation of Wellingtons, which - believing some authors - was not existent.(!?)

Regards,