DV
Did any ground tradesman sign for the A/F, and did that A/F, iaw bla bla bla, require a seat check?
The SI did not go into such detail, but I can guarantee that tradesmen will have signed for checking the seat pins.
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.