The housing market just won't lie down and die.

House prices nearly doubled in the four years to last autumn, years when prices of most other goods were falling and pay was rising, until recently, by barely four per cent a year.

There were fewer first-time buyers in 2004 than at any time in the past 20 years - and it looks as if many of those who did get a foot on the ladder did so with the help of money borrowed against the inflated value of their parents' homes.

An economic bubble is just like any other bubble. It swells like a bubble, it quivers like a bubble and in due course bursts like a bubble. This post-Millennium housing market had every characteristic of a bubble - except that it never burst, even when the infusion of new money from first-timers evaporated. Prices have just stopped going up.

The easy explanation is that the economy is still doing rather well. Unemployment has been edging upwards for a couple of months, but so has the number of people in work.

Yet Nationwide reports a sharp fall in consumer confidence, with 45 per cent of the people in its survey talking of paying off their debts, and only nine per cent thinking of borrowing more. The collapse of Rover must have damaged morale severely across much of the West Midlands.

So far, though, nothing has happened to unleash a wave of forced selling by home-buyers whose personal circumstances have changed for the worse. And without forced selling, markets rarely crash.

There is another less self-evident factor. Since last August average earnings have been rising faster than the price of the average home. Halifax has been logging what it calls (confusingly for stock market investors) a price/earnings ratio. This is the multiple of the average house price to average earnings of full-time male employees.

This ratio peaked last July at 5.63, fell back to 5.45 in January then settled at 5.48 in February and March, which is as up to date as the earnings figures get.

That may not look dramatic- It is nothing like enough to revive first-time buying. But the direction is plain to see. And it is helpful - providing interest rates do nothing worse than stand still.

While that is the case, there is no reason why the housing bubble should burst. Indeed, if it does nothing in particular for very much longer it will stop looking like a bubble at all.