Cliff, not to spoil your tale, but could the answer to the problem, be as follows..... a lot of taxying on heat-soaked engines, especially if leaned-out, would be susceptible to pre-ignition....switch off mags, pull mixture back and an imperfect shutoff, combined with a slightly cracked throttle, would allow "dieseling".....In the late 1960's ,I took the keys from a new Transit van,after a 6 mile journey It continued to run,albeit lumpily, for over 5 minutes.....later cars and vans of virtually all makes introduced a solenoid air-valve to the inlet-manifold...switching the ignition off allowed the valve to open (spring loaded open, powerd shut) thus breaking the airflow over the carb. jets.......sorry about the thread drift!
I made the huge assumption that the Merlin had Carbs...the float-chambers must have been like kitchen sinks.
My mind still boggles at the vast expense in fuel, materials and time to fly a single mission.
Add in the number of man(and woman! ) -hours in support,planning and maintenance and the costs are awe-inspiring....then add in the cost in human life...truly a different world you lived in then.