London’s property-owning classes are looking increasingly smug again as barely a week seems to pass without fresh data that their homes are spiralling exponentially in value. The latest update from the Nationwide shows house prices in the capital up by an astonishing 18 per cent in the past year. It’s not just London, now, either: with price rises rippling out across the rest of the country, the feelgood factor is spreading. But should it be?

There are important objections to be made about the growing divide between London and the rest of the UK, as well as the plight of first-time-buyers having to borrow ever greater multiples of their salary (if they can afford to buy at all). Then there is the knock-on effect to prices in the private rental market, rising homelessness, the list goes on. Even homeowners who may think they are benefiting from the rises are in fact getting poorer if they ever hope to move to a bigger property.

But there is a deeper reason why we should all – including propertied Londoners – be concerned about recent house price growth rather than taking heart at its renewed vigour, which is that the strength of the market in recent years has sowed the seeds of its own volatility. Of course there are fears of a bubble and whether the growing price-to-income ratio is sustainable. The truth may be that it already isn’t sustainable, but for one factor: hot money.

London property has in recent years become the investment vehicle of choice for international capital seeking a safe haven, as we at Civitas detailed in a recent report. In the wake of the worldwide economic downturn, turmoil in the Middle East and super-loose monetary policy, our capital’s housing stock has soaked up billions of pounds in global capital flows. This has only been encouraged by George Osborne.

Having failed to usher in the export-led recovery he promised early in the coalition, the Chancellor instead latched onto house price inflation as one of the mainlevers of a consumer spending boom that, he hopes, will get the Tories through the next general election. He didn’t just bet the house on this strategy – he bet everyone’s house on it. It is an easy gamble to embark on because so many homeowners are too easily convinced that large price rises are in their own best interests.

But central to encouraging house price growth in an already expensive market is encouraging buy-to-let (and even “buy-to-leave”) investors, many of which are non-resident. There are arguments to be made both for and against overseas buyers,but one potentially catastrophic problem is already looming into view, the only thing worse than so much foreign capital driving up prices: that now this money suddenly vanishes.

As central banks begin to raise interest rates around the world, as sterling strengthens with the economic recovery, much of this hot money will disappear. The threat of this taking place within the next year or so is raised in a new report from Deutsche Bank but there have been warnings for some time. The consequences of this for the rest of the market, and for the wider economy, could be deeply unpleasant.

But investors using the housing market to make money, and the volatility that follows, are not the root cause of the problem. What lies behind all of this is a collective weakness among voters for seeing their properties grow in value. Hopefully this will recede as the number of people priced out of the market continues to rise. But until it does, politicians will never build enough homes to level out prices, and the economy will remain beholden to a rollercoaster housing market.

David Bentley is co-author of the Civitas report ‘Finding Shelter: Overseas investment in the UK housing market’.