However, Flt Lt Cunningham himself signed in the aircraft after the 4th Nov flight and this rather trumps everything. Unless of course the Reds have some arrangement which wouldn't surprise me.
Yes, but the A/F servicing would have been carried out after Flt. Lt. Cunnningham handed over the aircraft. The tradesman concerned would have had plenty of time to ensure the pin was fitted correctly, either with bended head or inspection mirror.
This may seem to be detail, but it is detail that the SI should have addressed. It was one of the first questions I asked myself.
DV