By some measures, President Trump has altered the perception of American foreign policy more in the past seven days than his predecessors did in the past seven decades. A nation that built its brand around the world as open to the world’s needy and ambitious is now viewed, after Mr. Trump’s immigration executive order, as closing its doors in a way it never did even after the Sept. 11, 2001, attacks.

By installing Johnson at the Foreign Office, May has brought in her own little Nixon – ready for the day she needs to go to China. The problem with all this political logic is that it’s for domestic use only. It’s not what the rest of the world sees. And, remember, that’s what this job is for: to be our nation’s chief diplomat, our face to the nations of the earth. It’s not just another piece on the Westminster chessboard.