Editor’s note: Spoilers for “Downton Abbey” followers. My phone rang at 10:30 last night. At my age, that in itself is cause for worry. I saw it was a friend of mine, and I prepared to drive to her house if she were sick or one of her dogs needed help. “Who died?” I asked her. “You know who died!” she sobbed. “I just watched ‘Downton.’ I knew you were watching it, too, and you’d understand.” The PBS drama of the servants and upper-class residents of a huge English estate had captured us, as well as most people I know. …