Coastal Command – Holy Island crash August 1942

Good evening folks.

I am researching my great Uncle, William John Knapp, RAF Observer for Coastal Command who was sadly killed, along with the rest of his crew, whilst out on an evening training flight around Holy Island, Northumberland, on the 19th August 1942. The crash I believe is coded ‘3’ ‘C’ OTU. Is there any definitive account of what happened that night?  Can anyone help at all?  I’m told Ross McNeill is known to be an authority??

Kind regards and many thanks

Teletran