Dear Mary | 4 October 2018

Q. I recently gave a jolly dinner for eight friends (some old, some rather famous), all home cooking, ending with petits-fours. The next morning, everything cleared away, husband out for the day, I relaxed by the open French windows, reading (still wearing my long Victorian nightgown). I was startled to see two of the guests smiling in, come to lend a book we’d talked about the night before. The husband, mildly embarrassed, looked out at the garden intently; the wife kept turning the pages of the book they’d brought. Neither showed signs of leaving. I determined to stay sitting comfortably, explained that I had decided to slum it as I was alone, and didn’t offer them coffee, as I felt it would prolong the awkwardness. What should I have done, Mary?
— Name and address withheld

A. Even with ordinary old friends/ neighbours, it is a real breach of etiquette to drop in without ringing first.