LAST weekend, I went to a jolly party at the moneyed end of the London suburb of Dulwich, where the houses are all double-fronted, the rooms double-glazed, the gentlemen double-breasted and the children double-barrelled. There was champagne, a tagine buffet, much talk of schools, adultery, MasterChef and Obama's Nobel peace prize.

It couldn't have been more haut-bourgeois if Coldplay had been there. Our host made a charming speech, his comely wife said some gracious thank-yous, their daughter's boyfriend called for silence – and then it happened.

He told the assembled gathering how long he and his beloved had been courting (murmurs of "Ahhh..."), explained how he loved her above all women (murmurs of "Mmmm"), then said, "At the risk of embarrassing you, darling..." and sank to one knee.

The collective gasp from the floor could have been heard in Watford. The guy was proposing! In public!! Mother of God. An actual chap was going down on one knee in front of a throng of family 'n' friends in London, proffering a ring, in its Asprey's box, and popping the question.

There was pandemonium. People who'd hardly been introduced started hugging. Tears sprang to the eyes of the woman beside me. Some of us (the hardened cynics) fixed our gaze on the girlfriend's face, in case it might be set in a rictus of mortification; but all was well and she mouthed the word "Yes!" It was like a perfect cabaret turn. "So lovely," gasped the woman beside me. "So lovely and traditional."

Lovely, yes, I gruffly concede. But traditional? Only if your life had been lived through a filter of American (and later British) romantic comedies, in which declarations of love take place in public, either in front of cheering friends or, ideally, total strangers.

Remember Cher receiving two proposals in crowded restaurants in Moonstruck, Paul Hogan confiding his feelings to Linda Kozlowski before a crush of subway travellers in Crocodile Dundee, Adam Sandler's emetic song-proposal to Drew Barrymore in front of 200 passengers at 30,000 feet in The Wedding Singer, Colin Firth's proposal in faltering Portuguese in Love Actually, or (since we're in Richard Curtis-land) Hugh Grant's suggestion, at a press conference, that Julia Roberts might, er, like to, you know, in Notting Hill?

These, and a few score other such scenes, have inspired hundreds of copycat public proposals from romantic Americans from Seattle to Syracuse; connoisseurs of extreme tackiness can check out the way they organise these things in Main Street, Disneyland, all tumbling dancers and jazz-hands.

But has the phenomenon penetrated behaviour this side of the Atlantic? Have we evolved from a race of sheepish non-romantics, terrified of public speaking, to a genus of grand-standing extroverts who want the world to witness the most vital Q&A session of our lives?

So much is against it. One, you're having to reassure a large gathering of people that you're really keen on your beloved, as if your devotion might otherwise be thought specious or improbable. Two, the awful abasement of that kneeling gesture – one thinks of Lady Bracknell in The Importance of Being Earnest, catching Jack Worthing in the act of proposing to her daughter: "Rise, sir, from this semi-recumbent posture. It is most indecorous."

And of course, three, the strong likelihood that your girlfriend objects to being put on the spot/is experiencing PMT/absolutely loathes the cheap ring you bought in F Hinds the Family Jewellers/has just had a row with your mother/is contemplating having a crack at your brother/has been secretly giving you until Christmas to become less of a cheapskate, or else.

YouTube is full of dreadful moments, caught on camcorders, when a public question-popping was followed by the sight of the hapless non-fiancée fleeing the room.

How can men take the chance? But I'm wasting my breath. You just know more will do it in the future, shushing the crowd, fingering the ring, remembering their lines...

I'm a romantic. For love-struck men of action (such as the hero of Saturday night) who mimic the movies' let's-tell-the-whole-world strategies when asking for their girl's hand, I'm full of admiration.

But I dread the time when no social gathering, from church service to pub supper, will be complete without a chap, like a busker entering a Tube, dropping to one knee and loudly demanding that the blushing hoyden by his side makes him the happiest chap alive.

David Kenny is away