Francis Salway, the head of Britain’s largest property company, warned yesterday the market has peaked and is already showing signs of a slowdown. The Times

He said that some of the LandSecs' properties were now less valuable than they were last year, after enjoying rising valuations across its £15bn portfolio for much of the decade.

'Now a small proportion of properties will be worth less than they were six or nine months ago,' he said. 'This is a big deal. We have had four years when everything was going up.'

Although the value of Land Securities had increased by £1.9bn in the year to the end of March, Salway said: 'The year-end valuation of our investment portfolio showed a slowing in the rate of growth in capital values in the second half of the year. This is consistent with our view that the yield repricing of UK property assets is close to having run its course.'