You won't find any spoilers here for Primeval Series 5, Episode 6 here. (That's not what this is about.)
What I will say is that this was one of the better episodes of Series 5, let alone Series 4 of the show, and to be honest, while it had a plot twist that I expected, there were a couple of things that happened that I didn't expect. The story that has been building since the character of Matt Anderson was introduced back in Series 4 of Primeval was resolved in a manner of speaking, but left an interesting cliffhanger at the end of it all, and the character of James Lester shone in this episode (and the previous one). What made this interesting for me was that a character that I really didn't care for when he/she was introduced became likable over the course of this last pair of episodes, and I find myself quite fond of them now.
What makes this Series 5 finale of the show so interesting is that ITV won't commit to a new series of Primeval until some time when or after the show airs on ITV itself, as it's just finished airing on a small satellite equivalent channel called Watch. This means that when a new series of the show could be shot, maybe showing up in 2013 or so, it's possible that none of the current cast of the series might be in it!, depending on their work commitments and the like. So in the meantime, we just have to sit back and wait and see. What I can say after the end of Series 5, Episode 6 is that I want *more* Primeval, dammit! Make of that what you will.