“I’ve got some great news Mum!”

“What’s that?” I asked, raising my eyebrows a fraction.

“Zaid and Ryan say they’re going to stay at school until Year 12.” Raptor smiled.

Friends come and go like buses

“That’s good,” I said, and thought, “we’ll see about that.” Not because I’m expecting Zaid and Ryan to flunk out before Year 12, but because there’s a high chance their fathers will get posted to Singapore or some other far-flung corner of the world well before then. Either that, or the family will decide to repatriate – or switch to a new school offering an astronaut cadet programme.

It’s a big problem in expat schools – your kids make friends, and then their friends pack up and leave. Sometimes overnight. “Noel never even told anyone he was leaving,” Raptor said to me. “He went back to Finland … And then there was Horace. He went to Germany forever. And Hanna went to … erm,” His eyebrows snapped together. “I can’t remember.”

“Hungary,” I prompted.

“D’you remember Corner?” he asked. “Who always used to sit in the corner?”

I nodded.

“Well he left.”

Then his face softened. “And Morgan went to a different school.” His girl crush, now in a nearer, American school. And Eva and Omar – the list went on.

We haven’t got to the point yet where a school friend is off sick with a cough and all their classmates assume they’ve left, but it is something that, as a parent, you think about: Will they assume all relationships are transient? How much are they really affected by these lost friendships? Or, worse, perhaps they’re so used to it they barely notice?

Adults, of course, are equally as likely to lose friends in expat societies. I sat on a small, hard chair recently at Raptor’s back-to-school night, and realised I didn’t know anyone. At a school we’ve attended for five years. (Each year, they mix up the classes and so Raptor started the term in a class filled with different and new faces.)

A group of ladies were listening to a mum whose eyes looked a little too wide awake. She ran her hand through her hair, bracelets jangling, holding court. A new girl feeling swept over me like a cloak, transporting me back to the awkward, pimply, teenaged me on my first day of big school.

The start of the meeting was delayed as the head finished his speech downstairs, and after 10 minutes of shifting in my seat, someone I knew finally walked in. An Italian mum who’s been at the school almost as long as us.

She strode over and gathered me into a hug. She smelt like a posh department store, her earring pressed hard into my cheek. “How was your summer?” she trilled. We swapped very brief highlights. Me: Isle of Wight. Her: Los Angeles.

And, by the way we greeted each other like long-lost friends, I wondered if she had that fish-out-of-water feeling too.