That seems to be the view of all the people following the Guardian blog about it too. I'm not wholly convinced - would she really drive a nail through someone's hand? But I do agree that she was not an innocent bystander in all this
I've just finished binge-watching the third series of this, having also watched the second series. It is absolutely firkin superb. Superbly acted, excellent stories and very intelligently and sympathetically handled on all levels.
We will be catching up with the first series, because Tom Courtenay has always rated very highly with me as an actor, and if there is to be a fourth series, we look forward to it.