As the Jubilee celebrations reached their climax, some Conservative MPs thought it might be a wizard wheeze to give the Queen a surprise present: her 15th prime minister. The candidate’s name was as yet unknown, but that was of no consequence, since the purpose of the exercise was to remove the 14th incumbent, name of Johnson. It is a measure of the precariousness of power that one can watch a national pageant on Sunday just after receiving news that one might cease to be prime minister by mid-evening on Monday.