Artemio, who isn’t listening, now perks up. “I know, let’s test him!” he bellows. “‘Hello, Morgan, here’s a good boy, have some pork. Bacon—num num.’ He eats bacon, doesn’t he? Let’s try giving him some chipolatas!”

Kate does not permit herself a smile. “Listen to me, Artemio.” She catches his eye for a moment in the rearview mirror. “For us, religion’s private, right?”

“Maybe his dad’s a suicide bomber!” Artemio shouts, gleeful now. “Don’t they have loads of terrorists in France? Maybe that’s why nobody knows who his dad is. Maybe his dad’s Osama bin Laden! He looks a bit like Osama bin Laden, doesn’t he?”

“Enough!” warns Kate.

“Maybe they’ve come here on a suicide mission, him and Celia. Maybe that’s why they’re always wanting to see places like Buckingham Palace and Big Ben! Boom! Wouldn’t that be cool?”

“Depends what you mean by cool.”

“We could foil their plans! I could, like, take my X-ray missile launcher and zap them with it!” Artemio’s making a rocket with his forefinger, firework noises with his mouth.

Miraculously, there’s a parking place on their street. Kate pulls in. “Artie, bring that bag that’s in the backseat, all right, darling? I’ve got a ton of shopping in the boot.”

Artemio, as usual, climbs out of the car and starts towards the house, without either bringing the bag or closing his door. “Do those men really believe if you blow up a building or a plane or lots of innocent people you go to heaven? Mum? Do they really?”

“Artie, come back here. I told you to bring my handbag. And please don’t leave the car door just—”

She ends up piling the bag on top of her two armfuls of groceries. Fumbles with the front-door keys.

“Mumma?”

“Yes, darling?”

“Why do you and Daddy have to talk French to them all the time? It sounds so silly.”

The house is empty. Kate casts a quick eye around the kitchen, peeks into the spare room. Their guests must be out for the afternoon. She wonders where they manage to go for so long. They can’t just be hanging out in Queens Park all day. Should she be worried?

Having as yet no teenage child of her own, Kate has little sense of the correct boundaries, what a fifteen-year-old girl should and should not be allowed to do in London. Was it rash to have given Celia an Oyster card? The mobile’s proved less than useless, as every time Kate actually tries calling to find out where they are, it turns out Celia’s left it at home, or has it switched off in her pocket.

“What did you say, my darling?”