I taught at Marlborough for a short while in the 90's and loved it. It was a good mix, whilst there were some very rich kids there (one Chinese 6th former I taught personally owned flats in Manhattan, Mayfair and Hong Kong!) there were also pupils on bursaries from much lower income families, eg the school had special arrangements for the children of clergymen. Full fees are just shy of £30k pa now, btw, needless to say none of my kids went there!
And, for interests sake I wish to add that my grand daughter attends the same "exclusive" school that Kate Middleton attended. My grand daughter is on a bursary and my daughter is a hardworking single parent with no special "connections", she just sweats blood most of the time making ends meet.