Theresa May has become accustomed to her isolation in Brussels. It began six months ago, when she stood alone in a crowd of embracing leaders with no one to talk to.

At the end of last month she was seen trudging, weary and alone, to a waiting car as others digested her offer to European expats in Britain. Her marginalisation may have started there, but it is spreading.

In Hamburg, at the first meeting of world leaders since she lost her majority in the general election, Mrs May cuts a lonely figure as she, and Britain, ponder their place in the post-Brexit world.

Boris Johnson, the foreign secretary, has been bullish about “global Britain”, predicting that Brexit will set the country free to reach a