Lucy Lanigan-O'Keeffe teaches outdoor learning and mindfulness at Thomas's Battersea, where George has been a student for two years. Photo / Getty Images.
Some plump for a supermarket bottle of claret or a scented candle. Some club together with other parents, pooling their gratitude before showing it in the form of an Amazon gift card.
But if you're the future King and Queen, it seems you go further when choosing a gift for your child's teacher. A lot further: you set them up with their future husband.
That's one theory about what might have happened anyway, as it has been announced that Thomas van Straubenzee, a lifelong friend of the Duke of Cambridge, is engaged to Lucy Lanigan-O'Keeffe, a teacher who works at Thomas's Battersea – the prep school attended by Prince George.
Van Straubenzee, a 36-year-old estate agent, was previously married to the Duke of Northumberland's daughter, Lady Melissa Percy.
They divorced in March 2016 on the grounds of his "unreasonable behaviour". Lanigan-O'Keeffe, meanwhile, is from Co Kilkenny, Ireland. At just 31, she is the assistant head at Thomas's Clapham, but also leads mindfulness classes at its sister branch in Battersea.
Van Straubenzee and Prince William go way back. He and his brothers attended Ludgrove School in Berkshire with William and Prince Harry, and he accompanied the former on his first solo royal tour to New Zealand in 2005.
He was an usher at the royal wedding six years later, and is godfather to Princess Charlotte, who will start at Thomas's in September. She, with Prince George, could play a role at the van Straubenzee wedding.
It has not been made public who introduced the happy couple, but it seems a fairly safe guess that the mysterious matchmaker's name rhymes with "The Nuke of Dan's fridge". (Or Nukess).
Could this now become a trend, like so many other things the Cambridges do? We civilians must be prepared. So what are the rules of setting your children's teachers up with your friends? Before the end of term, read and heed – future happinesses may depend on it.
Do...
Check the teacher is single first
Really important, this. Imagine the scene at the school gates...
"Miss Clitheroe," you begin, "you look ravishing this morning. Yes, we got the letter about the headlice outbreak - Nanny's been informed. Now, we were just saying how you always seem so uptight, and Caroline and I wondered if you could do with a little male company? We showed your LinkedIn photo to our friend Milo – top chap, in commercial property, divorced, raring to go – and he wondered if you'd like a spot of supper?"
... Only to be informed that Miss Clitheroe is, in fact, happily married. No amount of scented candles will dig you out of that one.
Feel confident they'll last
Another crucial one, because the alternative might get awkward – for you and your child. For instance, consider what happens if you set your daughter's maths teacher up with your best friend, then your best friend breaks the teacher's heart? Extra algebra homework is what happens. Regular detention is what happens. No chance of that dream place at Oxford reading PPE is what happens. Another young life ruined is what happens. All I'm saying is: be sure it'll work.
Know when, and when not, to mention it
"Enough about Olivia's dyslexia, has Kevin called you back?" Under no circumstance is this an acceptable thing to say at parents evening, however much you need a distraction from your Olivia's recent behaviour.
In this situation, the teacher is on duty, acting as the educational and (in Lanigan-O'Keeffe's case) mindfulness guardian to your child and nothing more. See also: mentioning it at the annual parent teacher association meeting, mentioning it on Mumsnet, mentioning it in front of other parents/children/teachers...
Don't...
Threaten the teacher
A good look: subtly introducing your child's single teacher to your single friend, then stepping away and expecting no benefit from it, beside altruistic joy. A bad look: using your matchmaking generosity to bribe your child's teacher into giving them preferential grades and treatment for the rest of their school career.
"I can un-set you up with Howard just as easily as I set you up, Karen…" you might say, sliding their poor exam results back over the desk. Don't go there.
Involve your child
I don't imagine a Kensington Palace statement clarifying whether or not Prince George has been informed of his teacher's romantic relationship is imminent, so we'll have to resort to guesswork and assume he has. But beware. George is a well-behaved child: he has discipline and discretion built into his DNA. Your children, on the other hand, might be insolent little blabbermouths. And then what?
"Annunziata, hold your cup with two hands or you'll spill it," your child may be chided, gently. "But sir," the little madam will respond, "my mummy's friend said you can't hold your drink either." If you socialise with their teachers, loose lips sink ships.
Do it multiple times
Nobody wants a reputation in the playground for forcing all their single friends on the teaching staff. Nor does anybody want to create a toxic staff room, where half the science department have been courted by your husband's best man. So if it doesn't work the first time, perhaps leave it there and revert to the claret.