In an otherwise unremarkable article about how a British Airways passenger, barred from the plane’s lavatory, had wet herself, I noticed something that chilled me to the bone – even more than sitting in my own urine throughout a transatlantic flight would have done. The airline, it mentioned in passing while reporting how some schoolchildren said they’d been refused water (BA seems to be operating a none-in/none-out policy when it comes to fluids), doesn’t accept cash for in-flight purchases.

This is a deeply sinister development, made more so by the fact that it hardly seems to have been noticed. “Why’s it sinister?” you may be asking. “I’m sure there are sound practical reasons – no one wants airliners struggling through the sky weighed down by thousands of 50ps. And who doesn’t have a credit or debit card these days?”

Not many, I admit – just a few parched schoolkids. But cash is money in its most basic form. The airline is effectively saying it doesn’t accept or recognise money any more. Coins and notes with the Queen’s head on them, endorsed by a sovereign state, are no longer sufficient. It needs to know who we are – it needs to take its payment by tapping into each individual’s credit source. The electronic endorsement of a bank, an organisation accountable to no one but its owners, is required.

This isn’t primarily BA’s fault. I’m sure all big banks and retailers want to try it. No dirty cash pushing up insurance and security costs – everything nicely kept track of: where the money came from and where it went. All that data building up so that, as and when the law allows, it can be ruthlessly exploited for marketing purposes.

It’s great from the state’s point of view too. If anyone it considers dodgy is spending money, it has only to contact the bank and the credit access can be turned off like a life-support patient’s drip. The slow insinuation of the futuristic-sounding concept of a “cashless society”, conjuring up the wholesome Californian feel of the “paperless office”, is primarily in the interests of large and powerful organisations.

One might almost suspect it was no accident the new fiver had animal fat in it. Expect the next £20 to be gummed together with GM crops and foie gras and with a picture of Jimmy Savile on the back.

This may sound paranoid – credit cards are convenient and most people have nothing to hide. Why does it matter if all our payments are traceable? Just because someone is constantly following you around at a slight distance, it doesn’t mean they’re going to do you harm. But I imagine those who are constantly tailed really value a few hours’ break from it now and again. And, if asking for such a break, they’d probably be irritated if the response was: “Why? Looking for the chance to stare at some kiddie porn and plan an act of terrorism, are you!?”

The anonymity of cash has been an integral part of our economy and society for millennia. Getting rid of that is quite a step. Are we definitely going to get properly consulted on it? The government is already introducing an initiative called Making Tax Digital, which will give it unprecedented access to millions of taxpayers’ financial information. Who, in the current climate, is going to champion the cause of ordinary people retaining the right to buy stuff anonymously?

The internet makes all of these issues even more fraught. By the accounts of the print media and security services, the virtual world is an amoral anarchy in which super-villain can talk to super-villain and swivel-eyed loners are groomed by terrorist organisations and provided with easy-to-follow atrocity tips. On the other hand, it also has the potential to allow fully cyber-militarised governments to monitor almost all of their citizens’ activities and interactions. Sounds lovely either way.

Last week, Tim Berners-Lee, one of this hell-in-the-ether’s most well-meaning architects, sharply criticised the British and US governments’ moves to undermine privacy and net neutrality, saying the “human right… to communicate with people on the web, to go to websites I want without being spied on is really, really crucial”.

The home secretary, Amber Rudd, takes a different view: “We need to make sure that organisations like WhatsApp, and there are plenty of others like that, don’t provide a secret place for terrorists to communicate with each other.”

Seems reasonable. Except, if there’s no secrecy for terrorists, there’s no secrecy, or privacy, for anyone. Is that a price worth paying to fight Islamic State? Or is that surrendering our way of life, famously meaning that “they’ve won”?

But perhaps Isis and the security services can both win. In the first Metropolitan police statement after the Westminster attack, they portentously said they were treating it as a terrorist incident, thus darkly alluding to the Oxford 2nd VIII’s nefarious namesake. And it wasn’t long before that organisation claimed responsibility, though it didn’t seem to know the attacker’s name or anything else about the event it couldn’t have got off the TV news.

It struck me then that, on some level, both the home office and Isis wanted it to be Isis. They’d found common ground. Neither side wanted it to be a random nutter who’d hired a car – you don’t strike fear into the infidel that way and neither will it make the public acquiesce in greater surveillance powers. The same horrible, murderous event has occurred either way but if it’s Isis more people get something from it – including the media, which are justified in much more sensationalist rhetoric than if twice the number of people had been mown down by a non-radicalised driver drunkenly fiddling with his satnav.

To the elements of western governments seeking to increase their control over citizens’ lives, Isis has provided a wonderful opportunity: it’s just so absurdly evil and unsympathetic. This isn’t like the communist bloc, which, for all its totalitarian excesses, had a humane underlying philosophy. These guys actually make videos of themselves chopping people’s heads off. So, if presented with a choice between Isis and the Tories, or even Trump, or even Ukip, we’re all going to plump for the latter.

But it’s a false dichotomy. That’s not the choice. It would not be safe to give Isis the power of almost infinite surveillance over everything we say or do online, who we talk to, what we like and every penny we spend. But Isis isn’t demanding that. The only issue is whether it’s safe to give it to those who are.