Although it was surprising those two were in the bottom two, I don't reckon it's a fix. As with many of these reality 'talent' contests (the dancing/singing ones) I think a big infleunce on who people vote for is whether they know of them and like them. Personally although I know of Leon vaguely, even if he was good I would vote (if I voted, which I don't) for someone I know of better and like, such as Antony, Hayley, Alan (go Karl!) or Verity. e.g. I've never heard of Mark, and although personally I don't think he's very good, even if he was I wouldn't vote for him.
I'm just going on what I think and how I would vote, but I don't think it's fixed. One of the more well known people will win, like Hayley or Antony I reckon.