‘We don’t take cash,’ said the boy behind the counter in Pret after I tried to hand him a £5 note and two pound coins.

‘My’ ham and cheese baguette and bottle of Coke sat in a brown paper bag on the counter and a woman standing beside me grimaced as she waited to be served in the otherwise empty shop. I say ‘my’ in inverted commas because I have since looked into the legal rights concerned and what I might have said to handle this in an effective way. As it was, I got it wrong.

‘You have to take cash, it’s legal tender,’ I said. ‘I’m just following orders,’ he said.

I can’t believe people actually say that, but they do. I had a debit card in my bag, but I decided that if Pret was going to collude in this cashless tyranny we are being sucked into by stealth, then I don’t want to give them my money. If my £5 note is not good enough for them, they’re not getting my debit card tapped on their machine.

I turned and walked out, leaving ‘my’ baguette on the counter. I sent an email of complaint to Pret customer services, expecting nothing and getting worse than nothing in return:

‘Hi Melissa, We are sorry that we have not been able to give you the outcome you were hoping for on this occasion. Have a great day.’

Can these people hear themselves? I then set about researching exactly what the legal position is when it comes to shops refusing cash. It turns out they can refuse it… unless it is to settle a debt. The solution, therefore, is not to slam your cash on the counter and demand the shop take it. That is the wrong way around.

To have any chance of fighting this nonsense, you must take possession of ‘your’ sandwich, or whatever you are buying. Take a bite out of it in front of them. Unwrap ‘your’ baguette and gnaw the end; take the top off ‘your’ Coke and slurp it. Et voilà, you owe them money. They are legally obliged to take the notes and coins you are offering them – or postage stamps, for that matter.

When I can be bothered, I’m going back to Pret and I’m going to eat a sandwich in front of that young chap behind the counter who’s just following orders, and then I’m going to put five first-class stamps and 63 pennies down in front of him. And if he doesn’t like it he can call the police.

As for those cashless eager beavers who don’t get the point of all this, let me put it this way. A few weeks ago, I was in a chemist shop a few doors down from Pret and a row broke out because Cobham High Street was experiencing a total network blackout.

There was no electronic payment. A queue of people snaked down the aisles from the pharmacy counter and everyone was getting in a right state.

An old lady collapsed into a chair clutching her prescription. A man stood at the counter bellowing at the pharmacist about the tonic he needed, lest he perish on the floor that very second. He was one of those self-important types who live in a private road in a Surrey village such as East Horsley. No one, before him, had ever had a stinking cold.

He roared until he was puce in the face that they should make their systems work that instant. The pharmacist explained politely that he wasn’t getting anything unless he had cash. But not one of these people in this queue had any cash on them. It was astonishing.

Eventually, when everyone in the queue had taken turns shouting at the pharmacist, I stepped forward, took some notes out of my bag and paid for my items, saying: ‘This shows what a mess we will be in when there really is no cash, doesn’t it?’ and the ashen-faced pharmacist nodded.

Whereupon, the prat with a cold started shouting at me. I have thought a lot about what he yelled but have come to no definitive conclusion.

‘Have you ever been on a plane?’ he screamed. I think what he might have meant was that these systems work on planes so they should work in shops. But I heard something else. I took my items and replied: ‘No, I’ve never been on a plane, because I am a Brexit-voting, Trump-supporting ignoramus who carries cash around so I’m ready for doomsday. I don’t have a passport.’

He didn’t find that funny. And nor did anyone else. Everyone stared at me, as if I were the problem. I had planned to offer to buy the old lady’s prescription but I fled, before the cashless masses turned ugly.