For me, it began on January 4, 2017. My daughter, then 14, flashed her phone at me — I saw seven miniature figures jigging away to a cheerful, electronic beat. “Are they girls or boys?”, I asked, peering at the androgynous faces under dyed pink, platinum and scarlet hair. “Boys. They’re Korean. They’re called BTS,” she said, impatient at someone who did not instantly discern their genius (or gender). That was the start, though, of a Korean passion that has taken over the house — my life, perhaps, now even more than hers.

Next week, BTS play the O2, their first visit to London. Tickets were sold out in 90 minutes. I know, because I was huddled in a tent in Wales, trying to buy them over bad wifi. BTS spoke at the UN General Assembly last week. They’re bigger than Psy’s Gangnam Style, that first put “K-pop” on the world’s radar. There is a dark side to the industry, but it is just part of South Korea’s skill at exporting its culture and charm, as I’ve found.

Because it didn’t stop there. I would come home to find Korean chat shows playing on the TV (with titles such as Weekly Idol or Sexy Brain Problematic Men) — dating, cooking and games, with celebrities willing to make fools of themselves. The funniest captions were in Korean — so we learned the Hangul alphabet.

In case that sounds heroic, I should say it takes about an hour, thanks to an inspired monarch 500 years ago who wanted an easy alphabet for maximum literacy. I began doing grammar quizzes online as a cure for insomnia — and then finding professional reasons to follow Korean news, from Brexit to Trump’s trade wars and the brinkmanship with North Korea.

When my daughter showed a BTS video to a student who kept her company on evenings when I was late home, the young woman treated herself to a Korean trip — and moved there. And when our ancient Volvo died this spring, I found myself in a Kia garage under the Chiswick flyover looking for a Korean replacement.

So we went to Seoul this summer — and adored the friendliness. “We’re emotional people”, many told us. “That’s my husband over there — the marriage is not too bad, although we had a row this morning” said one acquaintance of 5 minutes.

There is a darker side, of course. The K-pop studios are notorious for the brutal pressure on their recruits (one girl band talked of the “paper cup diet” — each meal had to fit inside). There was shock when Jonghyun — front man of K-pop sensation SHINee killed himself in December. In a country where the source of wealth is often opaque, it is unclear how much reward the stars receive.

However, when I escort my daughter and friends to the BTS gig next week, I will silently give thanks for a pragmatic, cheerful culture, that has become an unexpected strand of professional interest, the music of which is now the undisputed soundtrack of my house.