“And,” added Polly, leaning closer and with a conspiratorial wink, “you don’t have to tell him it was from us—I know what teenagers are like, and a bit of parental kudos counts for a lot.”

“Thank you,” I said, and meant it. It was more than a CD—it was currency.

“Good!” said my mother. “Have you got time for a cup of tea and a slice of Battenberg?”

“No, thank you—I’m going to pick something up from Mycroft’s workshop, and then I’ll be on my way.”

“How about some Battenberg to go, then?”

“I’ve just had breakfast.”

The doorbell rang.

“Ooooh!” said Polly, peering furtively out the window. “What fun. It looks like a market researcher!”

“Right,” said my mother in a very military tone. “Let’s see how long we can keep him before he runs out screaming. I’ll pretend to have mild dementia, and you can complain about your sciatica in German. We’ll try to beat our personal Market-Researcher Containment record of two hours and twelve minutes.”

I shook my head sadly. “I wish you two would grow up.”

“You are so judgmental, daughter dear,” scolded my mother. “When you reach our age and level of physical decrepitude, you’ll take your entertainment wherever you can find it. Now, be off with you.”

And they shooed me into the kitchen while I mumbled something about how remedial basket weaving, whist drives or daytime soaps would probably suit them better. Mind you, inflicting mental torture on market researchers kept them busy, I suppose.