Agatha had brought a paperback with her and was trying to read by candle-light when Carol brought her a note. It said simply, “Come and join us.”

She looked across the restaurant. Just taking their seats at a centre table were Rose, husband and friend, and Olivia, husband and friend. They were smiling and waving in her direction.

Intrigued that such an unlikely combination should get together, Agatha picked up her plate and wine and went to join them.

“Isn’t this a surprise?” said Rose. “There we was, just walking down the street, when my Trevor, he says, he says to me, ‘Isn’t that Olivia?’” Agatha noticed Olivia wince. “And Georgie says, ‘Come and join us,’ so here we all are! Innit fun!”

To Agatha’s amazement, Olivia seemed to be making an effort to be polite to Rose, Trevor and Angus. It transpired that her husband, George, had recently retired from the Foreign Office, friend Harry Tembleton was a farmer, and that Olivia herself had heard of Agatha, for the Debenhams had a manor-house in Lower Cramber in the Cotswolds.

The wine circulated and Rose grew more animated. It seemed she was a specialist in the double entendre. She had a really filthy laugh, a bar-room laugh, a gin-and-sixty-cigarettes-a-day laugh, which sounded around the restaurant. George crossed his legs under the table and his foot brushed against Rose’s leg. He apologized and Rose shrieked with laughter. “Go on,” she said, giving him a nudge with one thin, pointed elbow. “I know what you’re after!”

Agatha did not think anyone could eat kebab off its skewer in a suggestive manner, but Rose did. Then she, it seemed deliberately, misunderstood the simplest remarks. George said he hoped there wouldn’t be another tube strike in London when they got back because he had some business in the City to attend to. “A boob strike,” cried Rose gleefully. “Has Olivia stopped your jollies?”