It's many political decisions, including, but not limited to: * Perpetual QE * Ultra low taxes on property (council tax) * Rules that allow foreigners to buy

It's many political decisions, including, but not limited to: * Perpetual QE * Ultra low taxes on property (council tax) * Rules that allow foreigners to buy property and not be taxed at all if they declare themselves non-resident. * Rules that allow tax evaders in foreign countries to stash their wealth here unimpeded. * Lower taxes on capital (dividends, capital gains) than labour (salaries). * A reluctance to build social housing in London.