This all seems reasonable. I am totally ignorant of RAF procedure but is it assumed that rearming simply means reloading? Reloading and cocking the weapons without any other cleaning or procedure (like replacing protective patches on the leading edge) would obviously be quicker in an emergency. The problem with cutting corners like that is that the weapons are more likely to malfunction in some way with potentially fatal consequences. I suppose in a single seat fighter aircraft you are less likely to have other people dependent on your fire! Also simply "running away" may be an option, one which is not open to soldiers operating a machine gun on the ground.
Steve
Steve