I must have missed this.

Some time over the past year or two London has become a post-cash society.

Yes, a few holdouts can be found, mostly among immigrant-run businesses that don’t like the idea of credit cards. Such as the Chinese noodle house on Wardour Street, in Soho. A pot of tea had already arrived when we spotted the “cash only” notation on the menu, and picked up and left.

To that point, we had gone nearly 24 hours and a dozen business transactions via credit card, in London. Including for a cab ride and a couple of small drinks at a theater.

So, after the incident at the Chinese resto, 10 minutes later and two blocks north, after being seated at the Hummus Bros. Levantine Kitchen, we asked the proprietor if he accepted credit cards.

He laughed. “Of course! Nobody in London uses cash anymore!”

This is a coming thing. Cashless living. Credit cards only, turning on its head the past four decades where cash was king and cards were viewed with suspicion and often not accepted.

Thinking back to the 1980s here. An American overseas could get by, most of the time, in First World countries, with a credit card — though it was always a good idea to check the decals on the store window, to make sure they accepted the sort of credit card you were carrying.

Bur just in case … travelers always had some Traveler’s Checks in his or her possession, in denominations of $20. Picking them up at your home bank was one of the details before an overseas trip.

Once you arrived in France or England or Italy, you would go to a bank and trade you traveler’s checks for the local currency, so as to be able to hand over “regular money” at the theater, at the restaurant, at the hotel.

(The checks came in books of five 20s, and you had to countersign on each travelers check while being watched by a teller. More than once I had a spot of trouble with the signature because I have never learned how to sign my name the same way five consecutive times. Never mind 10 or 20 times.)

When it became possible to pull cash out of a foreign ATM, maybe 20 years ago, traveler’s checks disappeared almost over night.

But now? ATMs in front of banks have nearly disappeared. In London, anyway.

Those bank-linked ATMs seem to have been replaced by “free” ATMs inside small businesses, like the Pakistani grocery we stopped at to buy some water.

The guy at the counter said we needed to spend at least five pounds to be able to use a credit card. So we put the water away and left.

At the hotel, we bought water and it was added to the room charges — which is being paid for via credit card. Of course.

We found another holdout the next day; a small bakery which seemed to be run by Poles. They also did not accept cash. Since this was breakfast, we finally broke down and went to the same Pakistani grocery as the night before, but this time withdrew 20 pounds.

We found out how “free” works. No apparent fees, up front, but whoever is behind this particular ATM was charging a huge markup to “exchange” money.

At this writing, one pound costs 1.18 euros. However, the “free” ATM charged us 1.30 euros for one pound, a hefty markup. Good thing we bought only 20 quid.

So, who is hurt by the disappearance of cash? The consumer, a little. Such as at intermission at the theater — the ice creams being sold by a kid with a mini-fridge … he needed cash and we had none, so no ice cream.

Small-business owners leery of credit-card fees. For now, they think they don’t need small deals from people not carrying cash, but the trend clearly is toward “cashless”.

Also, buskers may be about to go out of business.

We have seen people playing instruments, or singing, on the streets of London, and even if you like what they are doing, if all you have on you is a couple of credit cards …

That business model may soon go the way of the dinosaur. No coins to give the buskers, even if you wanted to. And how can a busker take a credit card?

So, this cashless thing. I like it, mostly, though the holdouts on the other end of business transactions can make things difficult, for now.

I assume this will all work itself out, over the next few years, and eventually everyone will accept credit cards. It makes too much sense.

No cash in your wallet, no coins in your pocket, no fumbling to get correct change. And nothing for buskers.