If we are to take it that Number 1, as identified in ‘Fall Out,’ has been the Number 1 running The Village all the time, then surely he must know the reason behind the Prisoner’s resignation. This on the understanding that Number 1 is the alter ego of Number 6, and that being the case, why persist with the question “Why did Number 6 resign?”
Perhaps the doctor’s diagnosis of the Prisoner in ‘A B and C’ is correct, that it is an anguish pattern – an agonising mental disorder. It could be that Number 6 was still agonising over his decision of having resigned, and therefore he continues to persecute himself because of his resignation. And so relives that moment over and over in his subconscious. It is always possible that the Prisoner regrets having taken that decision to resign, perhaps seeing that as the reason for him being abducted to The Village!
Be seeing you