New York TimesBook Review|'The Long Weekend,' 'The Mistresses of Cliveden' and 'Fall of Poppies'New York TimesThe Dowager Countess of Grantham was not being waspish (necessarily) when, over a typical white-tie dinner en famille at Downton Abbey, she asked her distant relation Matthew Crawley, “What is a weekend?” Young Matthew, whom the sinking of the ...