London was at its best this summer: Platinum Jubilee street parties and celebrations for the longest-reigning Queen, pub dinners by the Thames, and all the best hotels, restaurants and guides booked up. The mood shifted considerably after the Queen died on September 8, with the official days of national mourning bringing hundreds of thousands of mourners (including David Beckham joining at 2 a.m.) to the miles-long queue to see the Queen lying in state, 24 hours a day.
This fall, the U.K. is so...