Following a stunningly successful royal sojourn, after the parade comes the dustcart, and the arrest of former FBI boss James Comey reminds us that there is no staying the darkest impulses of this implacable president, says Anne McElvoy I t felt good to watch in Washington DC, as King Charles and Queen Camilla ensured maximum bonhomie without pandering to a tricky host. Chequered transatlantic history was woven into a story of staunch affinity, 250 years after what President Trump might call “