The chief executives of these companies do not want to build vast numbers of homes and risk depressing the market.

Instead — and some are quite open about this — they want to build as few homes as they can sensibly get away with because that it is the best way to keep prices high, profit margins up and their shareholders happy.

Far from embracing the free market and competition, they are behaving like monopolists and rationing supply — as Adam Smith predicted businessmen would when they thought they could get away with it.

There is another aspect to this. Because these quoted housebuilders are vast, they are only interested in big developments.

That means most of those inner-city brownfield sites and derelict industrial parks clearly visible on any train journey out of the capital — or indeed any provincial city — are of little interest to them because they are too small and because clearing toxic waste from brownfield sites is a lot more expensive that bulldozing a nice clean bit of agricultural land or a former playing field.

So the derelict sites stay derelict and pressure builds on the green belt.” …