Yes, Arthur, I would bet good money that's exactly who she means.

Minerva swears there's nothing much they could have told the viper. I mean, it could be that he revealed we've got operatives there at the school, but if they suspected any of them - Minerva or Poppy or Pomona - they'd surely have said before now?

And at any rate, it sounds as if Bellatrix now thinks that Nick's 'Hogwarts contact,' if indeed that's what she got from him, is Quirrell. Well, it won't do us any harm, though I can't say the same for him. He'll have nothing to tell them, will he?

Poor fellow. She won't like that, not a bit.