Indeed. The problem is London (and other big city) commuting distorts the figures. The average fare is £5, so out in the sticks taking journeys like Sleaford - Lincoln, Stoke-Derby, Liskeard - Looe, you are hardly going to find the same demographic, and these are the services that are heavily subsidised, not the commuter lines and inter-city network which tends to be used by the better off.
It is true, that the railways were, to an extent, always the domain of the middle class, as is flying. It's because of the sorts of markets it serves and tends to trade on speed and quality, with a slightly higher price (although not always) compared to a bus. Which is why if you look at the demographics of bus users, it tends to be people that cannot afford cars and are travelling over small distances. Indeed, on average only 43% of bus riders tend to be employed (nearly half tend to be retired and 12% unemployed), and at the opposite end of the scale, the average person through Heathrow is on 80k per year. The railways fall somewhere in the middle, in fact, as a mode contain the widest demographic - with a slant of the better off travelling more and on longer journeys.
