There have been a couple of places, (particularly on the IMDB forums and some online blogs) theorizing that V is in fact Valerie, the acclaimed actress who was arrested for being a homosexual. I admit, that thought had never entered my mind. But for a large portion, I have wondered about the coincidence that Valerie's initials are V. The main thing that popped into my head was that Valerie was actually V's mother. Of course, they don't show her and her partner having a child or anything. But it was a pretty logical decision considering how attached V seemed to Valerie.
Anyways, as for the alternate theory that V is indeed Valerie, it doesn't seem all that implausible. As I mentioned, V seemed a little too attached to the story of Valerie. I can understand that it stemmed from having heard her story and being inspired to fight against the system because of it. But what of the Carsons? The lady doctor does call it 'Your flowers'. Then there is the coincidental similarity of "V" and "V"alerie. As V said, "There are no coincidences, only the illusion of one". Plus, we don't really know what happened to V at Larkhill. That terrible experiments were going on, we are shown, but not the nature of those experiments. Wikipedia describes V as a 'transsexual terrorist'. I was quite surprised by this since they didn't show it in the movie. It could easily suggest that Valerie had a sex change at Larkhill, and the weird experiments had morphed her anatomy and voice. We, after all, never get to see V's face. Valerie did have reddish brown hair and so did V when he removed his mask after Evey left.
But regardless of whether V was Valerie or not, he was still a he. And Evey fell in love with him, so that doesn't make her character gay as some people are suggesting.
If only they had delved further into V's past...