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!
500N has it right - definitely the Tall Poppy syndrome at work, probably from journos who'd be very reluctant to admit their own earnings.