The Economist: House prices: Bubble and squeak

In a thoughtful recent study David Miles, of Morgan Stanley, tries to explain the doubling of real British house prices in the past decade. Some of the increase, he says, can be ascribed to rising real incomes; a smaller share can be explained by increases in population; some can be put down to lower real interest rates (including the keener pricing of mortgages by lenders). However, a lot of it is speculative. Between one-third and one-half is due to increased expectations of house-price inflation. These amplify the effects of other factors. Faster increases in prices foster the belief that future increases will also be stronger, so that higher prices fuel demand rather than dampen it.

The need to explain so much of Britain's house-price inflation by a change in expectations, writes Mr Miles, “suggests that the current level of house prices may be rather unstable.” Once those expectations come down, real house prices are likely to fall. The trouble, of course, is predicting when.