I am nearly a third through. The bit that amuses me most is that Lady Carbury and her son, Sir Felix, remind me of a friend and her grown up son (who gets up late and indulges his vices till the early hours, makes her despair, but is very attractive to women).
Sir Felix's vices are gambling and spending money he has not got. He and his gambling friends pass around IOUs in the absence of ready money, but the creditworthiness of some of these IOUs becomes increasingly doubtful. I don't know, do you think there might be some analogy with the goings-on in the City of London, Wall Street and other financial districts, as exemplified by Mr Melmotte and the board of the South Central Pacific and Mexican Railway investment opportunity?