From Windsor, the president went to Chequers, a grand house near London that’s been the official country residence of prime ministers since 1920. Churchill spent weekends with his family there during the Blitz (and it was where his teenage daughter, Mary, complained about her parents’ excessive protectiveness). Chequers was given by Viscount Lee to the British state in 1917, the year of the Balfour Declaration, a document with which Britain committed itself to creating a national homeland for Jews in Palestine (a name imposed by Emperor Hadrian in the second century A.D. to extirpate Jewish identity after the ornery population...