I am sure that in the Leonard Mosley book he mentions that AG was in the front and the Spanish test pilot in the back for the actual flight.

Rings a bell with me as well.

Wasn’t it the Spanish AF Commendante, Santa Cruz(?) that flew with AG, seem to remember they had known each from the war, as he had been one of the Spanish volunteer pilots that flew with the Luftwaffe on the Eastern Front…??