It starts in Number 6's cottage, which as a reproduction of his own home can be seen as an allegory for his own space & identity, or else somewhat allegorical for his life before The Village. I want to try to make an allegory of the zener cards. I feel the individual cards could be allegorical (the cube for imprisonment, the wavy lines for changeability, the cross for contradiction, etc) but I feel that would be over-elaborate. Perhaps the cards could be understood as an allegory for humanity, taking the time to play a 'game' of the trendy folk-psychology of the time, in the midst of the barbarism of The Village.
Of course cards - at least in the offices of the time - also referred to keeping records. The zener cards could also be allegorical of the way Number 6/we shuffles reality round to suit ourselves, or if you want to be countercultural, could refer to the way the Powers that Be shuffle people's lives around to suit themselves.
In a show where the protagonist is insistent that he will not be numbered, filed, etc, this is an ironic allegory, made more so by the fact that Number 6 becomes Number 12. In a world where it's a case of 'six of one, half a dozen of another,' it could almost be that the transformation on Number 6 into Number 12 makes him into a round dozen, symbolising a whole man, for the first time. Whether or not the Village is Number 6's own creation or dream refuge, the episode is allegorical for him resisting his own human growth, mediated by his own creation. Number 6 really is in the ultimate position of self-contradiction.
In fact the 'six of one, half a dozen of another,' motif is reflected in the colours of Numbers 6 & 12's blazers - they are plainly never intended actually to be exactly the same. This is perhaps the most obvious allegory in this episode - the black & white theme is also seen in the penny farthing badges. This subject has been discussed at length already in all sorts of fora - I'm forced to conclude that at least as far as the badges are concerned, inconsistency in colouring & placement has prevented anyone coming up with an incontrovertible meaning for them.
As for the blazers - I'm afraid that contrary to most views they represent the most obviously Christian allegory in the whole show. I must also confess to another heresy underlying this opinion, & this one's a real heresy - I believe Christianity to be a dualist religion in denial of its dualism, for example -
'Since the beginning the Christian faith has been challenged by responses to the question of origins that differ from its own. Ancient religions and cultures produced many myths concerning origins. Some philosophers have said that everything is God, that the world is God, or that the development of the world is the development of God (Pantheism). Others have said that the world is a necessary emanation arising from God and returning to him. Still others have affirmed the existence of two eternal principles, Good and Evil, Light and Darkness, locked, in permanent conflict (Dualism, Manichaeism). According to some of these conceptions, the world (at least the physical world) is evil, the product of a fall, and is thus to be rejected or left behind (Gnosticism). Some admit that the world was made by God, but as by a watch-maker who, once he has made a watch, abandons it to itself (Deism). Finally, others reject any transcendent origin for the world, but see it as merely the interplay of matter that has always existed (Materialism). All these attempts bear witness to the permanence and universality of the question of origins. This inquiry is distinctively human.' (Paragraph 285, http://www.vatican.va/archive/ccc_css/archive/catechism/p1s2c1p4.htm)
And yet I personally can't see how another quotation from the Catechism of the Catholic Church can be interpreted as meaning anything other than dualism:
' "Man, enticed by the Evil One, abused his freedom at the very beginning of history." He succumbed to temptation and did what was evil. He still desires the good, but his nature bears the wound of original sin. He is now inclined to evil and subject to error:
'Man is divided in himself. As a result, the whole life of men, both individual and social, shows itself to be a struggle, and a dramatic one, between good and evil, between light and darkness.
'By his Passion, Christ delivered us from Satan and from sin. He merited for us the new life in the Holy Spirit. His grace restores what sin had damaged in us.' (Paragraphs 1707-8, http://www.vatican.va/archive/ccc_css/archive/catechism/p3s1c1a1.htm)
This dualism is perhaps best seen in the Easter liturgy. This is the Cardinal Archbishop of Westminster letting the dualistic meaning of the Easter liturgy slip, without meaning to:
'This Easter Vigil is a celebration of light and life: the triumph of light over darkness and life over death. Nothing could be more stark or more important. As we celebrate these truths, every moment of our life on earth is transformed. We live either in the fear of encroaching darkness and death or we live in the firm hope of the victorious light and resurrection of Christ our Lord.' (http://rcdow.org.uk/cardinal/homilies/easter-vigil-1/)
It is exactly this dualistic either/or view that is the subject of this episode. When Number 6 becomes Number 12, he is clothed in a black blazer, indicative of his 'darkness', until he admits he is Number 6, when he will be clothed in white, indicative of his enlightenment. The whole thing is purely a psychological trick to make him say 'I'm Number 6'.
Perhaps the episode is open to a more orthodox Christian interpretation: in fact it almost warns against falling into dualism, since Number 2 makes the mistake of thinking that the man must be either Number 6 or Number 12, & apart from a factual error, the man who gets into the helicopter is, on an allegorical level, both Numbers 6 & 12 at the same time.
I notice when I wrote about this episode before I focused more on the institutionalisation approach - going to such trouble merely to get Number 6 to insist on being Number 6, which is supposedly not what the Village authorities want from him anyway. I think this episode may be better understood in those terms than in allegorical terms, despite the very obvious allegory involved. As an episode of The Prisoner, I'd have to say it's not one of the stronger ones: the plot is chock-full of holes, which become more obvious with repeated viewings, but it's carried through by the excellent visuals. The plot failures would include the pointlessness of the exercise, the easiness of Rover getting one of the clones as a resolution.
Ultimately Rover's little mistake gives Number 6 something to capitalise on. He makes a point of pretending to be Curtis, seeing this as an exit strategy. So perhaps it is ultimately an allegory of the man who insists of being himself against all the odds, & who triumphs as a result.
I just have one question - what is Steed's library doing amongst the other books in Number 12's cottage? - the distinctive spines with a black & a red band together are very apparent. Apart from that, of course, the more conservative furnishings of Number 12's cottage may represent the establishment figure that the Village authorities want Number 6 to become.