"In the year 2478, The Post Holocaust Pope, Nostromo CVI instructed me to find a passage to India, recently obliterated by The Laser Wars. My sister Carrie, a Carmelite, attended me. As our donkeys crossed The Bridge at San Luis Rey she turned to me outraged and blurted out : Let's get to the heart of the matter, Ignatz! I've wanted to tell you this for fifty years. You're a lousy cleric, a lousy counselor and a lousy bingo caller. Mom was right: You never left the age of innocence."

I continued to play with my yo-yo.

We argued, point counter point, until she lost control and launched me into the ravine below. As I lay dying, I heard
her breathe a sigh of relief.

"Finally", she whispered. "Deliverance!"

Wikipedia tells me, Frank, that a dowager 'in common usage' can refer to any rich old woman who 'behaves with dignity' and I am sure Agatha behaved with dignity though I couldn't speak for Dorothy L. Sayers. Nice one.

Of course I myself use it only of the widows of dukes and belted earls, but then my great-grandmother was Countess of Paddington, don't you know.