He approached the exit at the same time as his grandmother, so he held the door for her. She was probably heading for the ladies’ room: he had a vague notion that old women had to go a lot. She smiled at him and turned up a red-carpeted staircase. He had no idea where he was so he followed her.

On the half landing she was stopped by an elderly man leaning on a cane. Dave noticed that he was wearing an elegant suit in a pale gray material with a chalk stripe. A patterned silk handkerchief spilled out of the breast pocket. His face was mottled and his hair was white, but obviously he had once been a good-looking man. He said: “Congratulations, Ethel,” and shook her hand.

“Thank you, Fitz.” They seemed to know each other well.

He held on to her hand. “So you’re a baroness now.”

She smiled. “Isn’t life strange?”

“Baffles me.”

They were blocking the way, and Dave hovered, waiting. Although their words were trivial, their conversation had an undertone of passion. Dave could not put his finger on what it was.

Ethel said: “You don’t mind that your housekeeper has been elevated to the peerage?”

Housekeeper? Dave knew that Ethel had started out as a maid in a big house in Wales. This man must have been her employer.

“I stopped minding that sort of thing a long time ago,” the man said. He patted her hand and released it. “During the Attlee government, to be precise.”

She laughed. Clearly she liked talking to him. There was a powerful undertone to their conversation, neither love nor hate, but something else. If they had not been so old, Dave would have thought it was sex.

Getting impatient, Dave coughed.

Ethel said: “This is my grandson, David Williams. If you really have stopped minding, you might shake his hand. Dave, this is Earl Fitzherbert.”

The earl hesitated, and for a moment Dave thought he was going to refuse to shake; then he seemed to make up his mind, and stuck out his hand. Dave shook it and said: “How do you do?”

Ethel said: “Thank you, Fitz.” Or, rather, she almost said it, but seemed to choke before finishing the sentence. Without saying anything more, she walked on. Dave nodded politely at the old earl and followed.

A moment later Ethel disappeared through a door marked LADIES.

Dave guessed there was some history between Ethel and Fitz. He decided to ask his mother about it. Then he spotted an exit that might lead outside, and forgot all about the old folk.

He stepped through the door and found himself in an irregular-shaped internal courtyard with rubbish bins. This would be the perfect place for a surreptitious smooch, he thought. It was not a thoroughfare, no windows overlooked it, and there were odd little corners. His hopes rose.

There was no sign of Beep, but he smelled tobacco smoke.

He stepped past the bins and looked around the corner.