This could mean borrowers are suddenly faced with higher monthly mortgage payments. There are also signals that the mortgage market is tightening, with so-called "mortgage rationing" becoming stricter.
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More stringent background checks were imposed as part of the Financial Conduct Authority's Mortgage Market Review, and there are suggestions from government that banks may be forced to limit the amount they can lend to 3.5 times borrowers' salaries. The average buyer of a home in London currently borrows 3.8 times their annual salary.
"So far, this is a signal rather than a fact of policy, but it shows the mood music in the country," Gilmore said.
The amount of money borrowed for mortgages steadied in May to £16.5 billion ($28.14 billion), according to the Council of Mortgage Lenders – another sign that borrowers and lenders are getting more cautious.
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At the top end of the market, the rush of foreign money into the country has slowed slightly, as the pound strengthens and values skyrocket.
"There is a growing perception that London is fully valued and the prospects for future capital growth have diminished," Yolande Barnes, director of World Research at real estate agent Savills, told CNBC.
"Prime London seems to have reached a high plateau."
Those predicting a soft landing point out that, for most of the U.K., there has not been a recovery in house prices comparable to that in London.
"I don't think there's a risk of a downturn," Barnes said.