In the bubbliest property markets, many mortgages are held by investors, who were speculating on higher prices.

ECONOMIST: America's property crisis

One might expect the problem to be most severe in the bubbliest of markets, where homeowners routinely find themselves owing twice the value of their homes.

ECONOMIST: House prices and mobility

Last month the Los Angeles Times dubbed it "outrageous and randy" while the Washington Post's Tom Shales said Norton was "one of the bubbliest imports from the UK since Tynant water".

BBC: Norton hits New York stage