Sentence:  Mother...considered that the exclusiveness of Peter's circle was due not to its distinction, but to the fact that it was an inner <WSD>Babylon</WSD> of prodigality and whoredom, from which every Kensingtonian held aloof, except on the conventional tip-and-run excursions in pursuit of shopping, tea and theatres. 
Meaning of the word marked with <WSD> tags:  Any city of great wealth, luxury and vice.