Drive to the Cotswolds to spend a long weekend at Yummy Mummy No 1’s second home. This, I should add, is the highlight of our summer, closely followed by the prospect of a week’s camping at my parents’ house.

“Why does she have two of everything?” asks my eldest son.

“Some people like even numbers,” I reply breezily. “That’s why she has two dogs, four en suite bathrooms, six guinea pigs and eight sofas.”

“Does she have two husbands?” asks middle son.

“No, she just has Mikail,” says eldest son in a matter-of-fact tone. “He is a great dad: he plays football when you want him to, and when I was on a sleepover, he let us watch The Mummy, gave us a whole tub of ice-cream and let us do Game Boy when we woke up.”

“Did he?” I say, taken aback.

Since we are stuck in a traffic jam on the M40, I decide this is the right moment to turn to the back of the car and explain to them, very clearly, that Mikail is the nanny, not Yummy Mummy No 1’s husband. And that her husband will be there at the weekend and might not like being confused with the nanny.

“He is her husband,” insists middle son. “He takes the children to school, cooks them dinner, plays football with them, and puts them to bed.”

“That would make him her wife,” I joke. “Look: Mikail is paid to do these things. Their daddy works very hard to earn lots of money so that…”

“…he can pay Mikail to do those things?” asks middle son.

“So she can buy things in even numbers,” says eldest son. Everyone seems satisfied with my explanation, and there is a lull in the conversation until we turn off the M40. I head into the rural hinterland and find the turning to Yummy Mummy No 1’s rural idyll. In a first, we have completed a journey without my getting lost or the children fighting.

“There’s a flaw in your argument,” says eldest son suddenly, using one of his father’s favourite phrases.

“What would that be?” I reply.

“She is an odd number,” he says. “There’s only one of her.

“It’s because they’re good at sharing,” he goes on, authoritatively.

“Who?” I ask, as I see Yummy Mummy No 1 and the male nanny heading towards us.

“Mikail and the man you claim is her husband,” says eldest son. “They’re good at taking turns.”

“Yummy Mummy No 1 belongs to their daddy, not Mikail,” I stress, as I open the door and urge them to get out.

“Then why does he sleep in the same bed as her?” asks eldest son.

“Don’t be silly,” I say.

“When I had a nightmare after The Mummy, I went in to her bedroom, and she was definitely having a sleepover with Mikail,” he says.

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