Interesting thoughts - thank you. The funny thing is - I chose her! It was months ago and I didn't really realise the possible implications - I just thought she would be a good person (her work is related) and my supervisors agreed. It was only on reflection that I thought, hmm, how is she going to be impartial? Along the lines of kikothedog, I can't help feeling that she will feel somewhat pressurized not to judge too harshly (i.e., fail/MPhil downgrade even if worthy of such) her close co-workers' (and quite possibly even friends') student's thesis, regardless of its quality (within reason). But on the other hand, she strikes me as a very professional and fair person. So maybe she wouldn't be constrained by politics in her role. Who knows! Funny old world, this academia.