Britain's love affair with China comes at a price

The trip may unlock funding for the Northern Powerhouse project, intended to revive Manchester and the great industrial cities of the North, along with finance for the HS2 high-speed rail link and a host of infrastructure schemes.

China has agreed to sell renminbi bonds in London, anointing the City to be its offshore hub in the Atlantic region.

The British gamble is that an open-door policy -- when the US and the EU reflexively treat Chinese state investors as a threat -- will lead to a reciprocal welcome for British firms in China.