I Am Not A Number, I Am A free Man
A central theme in the series was Number Two's attempt to discover why Number Six resigned from his position.
Many people as well as the series itself postulate that those in control of the Village are either testing Number Six, or actually want to know why he resigned. Even according to McGoohan during subsequent interviews, the answer is not clear. For if the Village is testing him, to see if he will tell his 'state secrets,' that is one thing. However, others suggest that the Village wanted to find why he resigned first, hoping that this revelation would unleash a torrent of other information. (At least one Number Two believes that it would: in "The Chimes of Big Ben", Number Two states, "If he will answer one simple question, the rest will follow: Why did he resign?")
In any event, following this encounter, Number Six appears to escape the Village. However, his ultimate fate is not revealed and in the closing credits as he enters his original house, the hearse—seen in the opening credits when the occupant gets out and gasses the Prisoner through his door letter box—appears to drive by again. In interviews, McGoohan has repeatedly maintained that " hasn't got ".
In several episodes, allusions are made that other residents in "The Village" are ex-spies, 'retired' without their consent. Number Six is known to have answered to at least two individuals known as simply as "The Colonel", as well as to another long-time superior named Fotheringay. These men are shown as being in league with the Village to one extent or another. It is also ambiguously (and menacingly) suggested that some people in the British government are in-concert with those who run the Village, regardless of who they might be.
It is known that he was engaged to be married to Janet Portland, the daughter of his superior, Sir Charles Portland, prior to his capture by the Village, though this doesn't stop Number Six from developing close platonic relationships with various women during his imprisonment.
Medically, Number Six appears to be the picture of good health. However, the episode "Free For All" reveals that he was required to eliminate sugar from his diet "on medical advice" (although he intentionally drops sugar cubes in his tea in "The Chimes of Big Ben" as an act of defiance). He claims rarely to drink in "Dance of the Dead", and is seen to smoke only twice—once a cigar, and once in a dream sequence. "The Schizoid Man" establishes Number Six as an at-least-occasional cigar smoker, as Number Two brainwashes him into preferring Russian cigarettes as a means of undermining his identity. Number Six has repeatedly been under the influence of psychotropic and hallucinogenic drugs, and undergone periods of severe mental or physical stress without apparent effect on his health, although he has occasionally been driven to exhaustion by his ordeals.
During the episode "Once Upon a Time", Number Six undergoes an intense form of brainwashing/interrogation called "Degree Absolute" in which his mind is reverted to that of a child and he is made to relive major events of his life. Given the nature of this interrogation and the motive behind it, it is not known for certain what elements of Number Six's life so portrayed are real and which are fiction. Among these events presented is the suggestion that as a young man Number Six was driving a vehicle and speeding which may (or may not) have resulted in a fatal accident. It is also suggested he attended some sort of private school and was once punished for not telling the headmaster about some of his friends' rule-breaking activities. Another scene from the episode suggests that he worked for an established British banking firm before someone (the episode implies it was someone connected with the bank) enrolled him to a top secret government job.
During "Once Upon a Time" it is also stated (with greater certainty) that Number Six flew a bomber in "the war"; exactly which war is not stated but evidently Number Six was shot down and captured by the Germans, which presumably means World War II, which is possible given his stated birthdate, if only just.
A few names are attached to Number Six in the series, but it's impossible to tell if any of them are real. In "Many Happy Returns" he identifies himself as 'Peter Smith'. Although it is possible that this is an alias, he does give it to a woman who has presented herself as the current owner of his car and tenant of his apartment. He in fact asks to examine the former's lease and the latter's log books, expressing surprise that both bear only her name. However, the house and car may have been acquired under one of Number Six's long-term false identities as a spy. In the episode "Do Not Forsake Me Oh My Darling", it is learned that Number Six possesses numerous code names: Schmidt, Duval, and ZM-73.
The connection between Number Six and Number One—the entity presumably in charge of the Village—is left intentionally ambiguous and has been the subject of debate and analysis since the final episode of the series aired. In "Fall Out", Number Six encounters a man who is supposedly Number One: upon removing two masks worn by him, a person who is identical to Number Six is revealed. This man quickly escapes and never appears again. Speculation as to the identity of this person ranges from a twin brother of Number Six, to John Drake, to a likely mind-straining hallucination. It may be of importance that Number Six's address number is N° 1.
Read more about this topic: Number Six (The Prisoner)