I am reminded of McGoohan's reference to Number 6 as an 'Everyman', & this episode reminds me strongly of the eponymous mediaeval play:
'The premise is that the good and evil deeds of one's life will be tallied by God after death, as in a ledger book. The play is the allegorical accounting of the life of Everyman, who represents all mankind. In the course of the action, Everyman tries to convince other characters to accompany him in the hope of improving his account. All the characters are also allegorical, each personifying an abstract idea such as Fellowship, (material) Goods, and Knowledge. The conflict between good and evil is dramatised by the interactions between characters. Everyman is being singled out because it is difficult for him to find characters to accompany him on his pilgrimage. Everyman eventually realizes through this pilgrimage that he is essentially alone, despite all the personified characters that were supposed necessities and friends to him. Everyman learns that when you are brought to death and placed before God all you are left with is your own good deeds.' (http://en.m.wikipedia.org/wiki/Everyman_(play))
The theme is inverted here, of course, because while Number 6 is apparently the subject, actually Number 2 is the real object he (Number 2 himself) is seeking. The moral therefore is really that the 'virtuous man' will triumph, & the man who has something to hide - from The Village, himself possibly, & certainly his boss, in Number 2's case - will fall. Now you may object that this is not actually what happens, since the plot really hinges on an apparent trick - but remember the whole point of allegory is that one thing stands for another. What if Number 6's 'trick' is to keep silent about knowing that Number 2 is a double agent? In that case there is a clear allegory about keeping silent.
Actually I'm quite happy to admit that I've probably stretched this episode as far as it will go in allegorical terms, alhough the three 'films' do make convincing scenes in an allegorical 'journey'.
In fact the allegory comes out better when the story is told from Number 2's perspective rather than Number 6's. I'm perfectly happy to see Number 6 as an incidental figure here. The allegory sounds something like this. Number 2 has been appointed to his role & tasked with finding out about a particular person. His dread at the phone ringing is palpable, & it is a task that gives him no pleasure. Under pressure he enlists the help of Medicine (in the form of number 14), who despite her better judgement agrees to help. Number 2 is prepared to risk, well, pretty much everything to find out the required information, & the experimental procedure begins immediately. The night-time setting & heavy rain are allegorical of Number 2's blindness, fumbling about in the dark, in a storm. The first images of Number 6's thoughts already suggest they are not going to find out what they want - he is thinking obsessively about the act of his resignation rather than the reason for it or the people he has been in contact with Number 2 ignores this suggestion that he is going to be on a fruitless errand. Number 2 wants to find out the nature of his relationship with A, B, or C, & footage of these people is fed into his thoughts.
A is allegorical for changeability, defection (literally), the expectation that anything can be purchased. Number 2 in this sequence is allegorical for solidity & reliability. I love the Citroen DS that he is abducted in, by the way: it is an allegory for sexy French motor cars. Number 2 does not notice the playful way in which Number 6 ends the sequence with 'Be seeing you,' indicating his independence of mind & preparedness to mock The Village, even under the influence of drugs.
Number 2 values life poorly, & regretfully accedes to Number 14's insistence that 24 hours must pass before Number 6 has the next dose of the dangerous drug. Number 2 is sufficiently naïve to try a softly-softly approach with Number 6 when he goes to confront him: Number 6 brings up the subject of having things to hide, but Number 2 ignores that. With greater dread he answers the phone & tells his boss he'll have the answers in two days.
The next night's suspect, B, is allegorical for seduction, all that is wily. While being 'a good spy, from a long line of spies', she represents the seductive arts, as opposed to the commercial or aggressive arts, which A represented. Unfortunately her wiles don't work, & when Number 2 manipulates the dream (here B is allegorical for Pity) Number 6 is of course not taken in.
Number 2 fails to keep an eye on the room in which the experiments are carried on, thus missing Number 6 diluting the drug, which will allow him to manipulate the procedure. This omission is allegorical for Number 2's belief that he is invulnerable. In fact Number 2 is becoming more vulnerable to being wound up by Number 6's civil disobedience.
C represents the unknown, & also represents Number 2's desperation. C is representative of the unknown elements of the known: the moral here is clearly not to think you've got everything sussed. Ultimately, of course, it back-fires, & 'D' turns out to be Number 2 himself! Surely the moral is about as obvious as it can get here?
I find it interesting the contrast between action in The Village, & outside of it in Number 6's 'dreams'. This reinforces the idea I've been mooting of The Village as representative of Number 6's dream escape, compared with the reality of the life he had been wanting to escape. Perhaps the truth should be sought in The Village, rather than the outside. I absolutely love the bit where he dreams about talking to Number 2 in The Village!
Having gone through this episode thinking about the allegory & rephrasing it from Number 2's point of view, I'm unfortunately forced to the conclusion that I may have pushed it further than it can go. It could certainly bear an allegorical interpretation, but the trouble is that the interpretation has to be forced onto an episode which essentially fails, in my opinion. It fails because it is a straightforward spy-fi interrogation story, already over-complicated by the frankly incredible means of interrogation. It would have been better if A, B, & C were merely referred to by people in the Village, perhaps even Mdme Angadine (remember she's not known to be C) could have been introduced to The Village, as Number 14 suggests.
However, the figure of Number 2 remains, as an allegory for the pressurised man in the middle, who resorts to endangering other people to get what he needs. Perhaps the final allegory here is cruelty & over-complication, leaving the good man free to walk The Village at the end.