speaker is almost certainly a Grande Dame (less likely to be a Grand Seigneur) in a novel set in Victorian, Edwardian or Twenties England. She says of the Universities of Oxford and Cambridge, something like, "..of course they are tremendously important; that is where we train our servants. Of course some of them do put on airs once they become frightfully upper servants, like Prime Ministers…" It is absolutely not Powell (far too broad) and not I think Waugh (or I would have run it down by now). It tickles me to the extent that it neatly anticipates Peter Townsend's anthemic, "…meet the new boss; just like the old boss".
My guess is that it is Alan Bennett or someone else from the review/playwriting fraternity, or someone like Hare or Brenton. But I really do not know.