Broster is taking a stand on some controversial topics regarding the battle: whether they should have made a stand at the Spey, which battlefield would have been the best, whether the Franco-Irish officers were competent or not. I note that mostly Duffy does not agree with her on these issues, though I'm sure opinions vary.

Oh interesting. I'm glad you're flagging these things! It's so easy to take even a novel as authoritative, when you (i.e. I) haven't read any alternative accounts.