Think of the astonishing technological advances we have seen since then — a computer in every pocket, the whole world an email away. All this, and we’ve not even won two hours back to sit down with some Dickens. And it’s hardly as though the economy has been going gangbusters to make up for it.

• Denmark is first in Europe to raise retirement age to 70

Where are all the productivity gains going? Who is getting all that free time? The short answer is: the young and the old. “The people who are actually living Keynes’s dream are the elderly,” declared the economist Tyler Cowen in a 2016 lecture at Duke University in North Carolina. “We choose to consume the bulk of our leisure when we are pretty old, and that Keynes had not expected.” When we retire now, we are looking at nearly 20 years on the state pension, up from 13½ in the 1950s.

At the other end of the spectrum, more than a third of us now go to university, so we start our working lives later.

So this is the social deal we’ve cut: keep slogging it out, only now we get slightly longer at the start — and much longer at the end — to chill out. Even the Danes will get 15 years of life after they retire. Except nobody really did sign up to this deal. It just happened. I’m not convinced this is the best way we could have organised our affairs.

It is time for all of us to consider retiring later. The economics of the present system just don’t stand up. In 2018, one in five of us were over 65. In 2050, it will be one in four. Fewer and fewer workers will be paying for more and more people’s retirement. Pensioner benefits already account for 11 per cent of public spending. The state pension system is a Ponzi scheme, and it is about to collapse.

• Rachel Reeves and Angela Rayner have their eyes on nation’s savings

This is a reality we face. We should use it as an opportunity to radically rethink how we work. What’s more, with the promises and horrors of AI knocking at the door, we are perhaps about to head into an age of even greater abundance than Keynes imagined. What should we do with it?

Well, we could continue to spend more and more of our lives in retirement. But is that what you would choose, if you were given a serious chance to decide how you would allocate your leisure days? I suspect for many the answer is no.

I’d rather spend about a decade of my life retired, and take a chunk out in the middle to be with my kids in their formative years. Perhaps I’d have had a year or two in my late twenties to study, while my brain still had a bit of its ever-declining elasticity.

You might allocate your leisure differently: perhaps you might want to work a three-day week for 50 years, or a six-day week for 20. Perhaps you might want to take every August off and decamp to Florence, or use your early sixties to help with the grandkids.

• How the UK became a nation of savers amid rising interest rates

This is pretty utopian thinking, sure. There’s a whole lot of legislation that would have to shift to make this possible, a whole lot of social attitudes too. We’d need to be better at getting parents back into the workforce after years of absence, better at retraining workers at any stage. We’d need to make employers better at understanding the value of older workers too.

Perhaps this is the very time for utopian thinking. We are on the verge of technological innovations reminiscent of science fiction, and we are meeting them with a social structure forged in postwar Britain, when life expectancy was 69. Think of the 69-year-olds you know now: for the most part they’ll be mentally sharp and in decent physical shape. What a waste to put these people on the bench for the rest of their lives. I know a 75-year-old judge who has just been forced to retire — that being the mandated retirement age for the profession. It’s absurd. This is a man who could have gone on for ever.

My utopian vision of a life of flexible leisure is probably not one you will get to experience. Nor will I. But I think it is something we should work towards, rather than just piling up retirement years. Call it, if you will, an Economic Possibility for Our Grandchildren. Wouldn’t it be marvellous if we could give them the “economic bliss” that Keynes dreamt of? Let’s check back in a hundred years and see how it’s gone.

Goodbye, vapes. Hello again, old smoky friend

Farewell, then, disposable vapes. On Saturday the long-awaited ban comes in and the sweet cloud of someone else’s watermelon bubblegum as you try to get to work will be no more. A devastating day for my generation, wiping out one of our three hobbies — leaving us with only scrolling and complaining.

I was against the ban when it was announced. I don’t like banning things in general. It wound me up no end when the last government banned nitrous oxide, because what people didn’t like about nitrous oxide wasn’t the drug itself, but seeing those little canisters everywhere on the street. Littering is already illegal. Surely the government should get a grip on that instead.

I followed a similar line of thought with vapes. Vapes themselves weren’t a problem; it was the government and the manufacturers’ inability to keep them out of the hands of children that was the issue. Why not crack down on that rather than just reaching for another ban?

But then I went to the corner shop and found myself looking at all the disposable vapes, in their array of electric colours and sugary flavours. Cherry melon. Pineapple fizz. But not a single good, honest tobacco. Not even a menthol. Right. These really are for children, aren’t they? It’s not a side effect; it’s in the design. So, sadly, it’s probably right they go.

As for the adults, I suspect many will follow the path of a friend of mine: she’s throwing a “goodbye to vapes” party on Saturday. After that, she’s going back to smoking.