"Whose side are you on?" "That would be telling"
We know whose side 'the village' are on right from Episode 1.
They're on HIS side.
When McGoohan walks in to the green dome for the fist time and meets No.2, they talk about his resignation - more to the point, the reason behind his resignation.
McGoohan is adamant he'll tell them nothing and then No.2 says, sympathetically, "Personally I believe your story..."
So there we have it. No.2 has read whatever was written in the 'Resignation - By Hand' letter which McGoohan slapped onto the desk of his superiors in London.
How else could he have gained access to the contents of it?