The Prisoner has no name, he has a number, that number is Six. He must have once had a name, but for some reason everyone, even his closest ex-colleagues, and his fiancee Janet Portland are reluctant to actually use his name!
We know that the Prisoner used code names, in France Duval, in Germany Schmitt. In the episode Many Happy Returns the Prisoner used the name Peter Smith, although I fancy that was made up on the spur of the moment. In Do Not Forsake Me Oh My Darling the Prisoner was also know as ZM73. When the Prisoner, in the guise of the Colonel was asked what his name is, the Prisoner asked real or code? "Code" was the reply. And after the Prisoner had given his fiancee Janet Portland a message only he could give, and having asked Janet who else could have given her that message, she replied "Only you." I mean how difficult could it have been to say "Only you John." That's right, John as in John Drake of Danger Man, for that is who I believe the Prisoner to be, the former John Drake. Only it was impossible to say on screen for the fear of having to pay the creator of Danger Man, Ralph Smart, copyright payments. That is why you never hear the Prisoner's name uttered in the series. Why the Colonel says to his ex-colleague "You're a stubborn man Number Six, instead of John."
Be seeing you