Good news at last for landlords. Last quarter the US residential vacancy rate declined to 9.4 per cent, an almost 1 percentage point drop compared with the third quarter and the steepest quarterly fall since 1966. This new-found demand means rents could grow at more than 2 per cent this year, says Deutsche Bank. So with rental yields almost two-thirds higher than their 2006 trough, and house prices still about 30 per cent below their corresponding peak, according to the Case-Shiller index, it might appear a good time to buy. The good news, though, may already be priced in.

A buy-to-let investor’s rationale may seem sound. Rental yields – at about 5 per cent – are about the same as mortgage rates. That means a tenant’s rent covers the interest bill and the owner pockets any capital appreciation. But although yields have risen strongly, they have merely returned to their 50-year average after being decimated during the housing bubble.

For yields to push higher, either house prices need to fall or demand for rental properties needs to rise. Given the unemployment rate is forecast to remain relatively stable at just below 9 per cent for at least the rest of the year, significant additional demand appears unlikely for now. Furthermore, when the Federal Reserve raises base rates – a move most economists expect by the end of the year – the symmetry between mortgage rates and rental yields may be blown away.