John,
No sweat ! Dad just talks (we old-timers are quite good at that), you have a recorder and do all the heavy work. I had a room mate at Spitfire OTU in '42 who had been a constable in the Met; a Reserved Occupation if ever there was; the only way they would let him out was if he volunteered as aircrew.
Seems the Burma Beau story fits the facts: the nav would have had to climb over the back of his pilot's seat and the pilot to get at the yoke.
No, we're not a nimble on our pins as we were then, but it looks as if you've shoehorned your Dad into some sort of cockpit: what was it ? And how did you get him in and out (block 'n tackle ?)
Happy days, Danny.