I was listening to two friends, both academics, talk: “Isn’t it weird,” one said, “that we had very radical ideas when we were undergraduates, but we’ve ended up in these very traditional, monogamous relationships.” “Not really,” said the other, “because I’m not interested in sex and I only like women.”

As the Bloomsbury set is small-screened for some generations and introduced to others in the BBC’s beguiling Life in Squares, it is salient – honouring, almost – to remember that they invented an idea. Maybe not for Europe, but for British culture as we know it: that if you’re intelligent enough, and you think hard enough – about anything – the normal straitjacket of morality doesn’t apply. All the requirements of propriety and nuclear family and monogamy melt away. If you abandon yourself to free thinking and intelligence, you become superior in every way, and that means, naturally, rejecting the contradictions and dishonesties that are necessary in the normal run of what it means to be good. When you put it down on paper, the mystery is not that we still find them fascinating, but that we didn’t all immediately become like them.

The Bloomsbury set had all the seeds for a different kind of life, beyond the fact that they could sleep with whomever they liked. From John Maynard Keynes, they had the beginning of the end of the world of work, the erosion of the relationship between production and wealth, and consequently, between work and identity: which led to the exploration of leisure as a noble calling, vital to the cultivation of the life of the mind. I scanned his famous essay, Economic Possibilities for our Grandchildren, to evidence this. He wrote: “For the first time since his creation man will be faced with his real, his permanent problem – how to use his freedom from pressing economic cares, how to occupy the leisure, which science and compound interest will have won for him, to live wisely and agreeably and well.” Then I found this equally famous, even more inspiring line: “The love of money as a possession … will be recognised for what it is, a somewhat disgusting morbidity, one of those semi-criminal, semi-pathological propensities which one hands over with a shudder to the specialists.” It feels so new. It makes you wish they were all still alive.

From Virginia Woolf, they had the urgent duty of honesty, the truthfulness of having fully explored one’s own mind, rather than the more reputable, less interesting version of not telling lies. From Vanessa Bell, Duncan Grant and Roger Fry, they had the concept of applied art, so that there needed to be no distinction between high art, design, philosophy, poetry, tablecloths: that living a complete life meant bringing creative intellect to everything.

These ideas are elementally persuasive, and could have changed the structure of society, of communities, of families, forever. And yet they didn’t: they burned in the lives of their creators and died with them, never to be replicated. They had as their highest values sex, fellowship and the life of the mind; they achieved that unusual – unheard of – thing of not having to put those in ascending order of importance, but instead allowing them to coexist and sometimes conflict. But rather than disseminating that as a way of life, they seemed to annex it, so that all the sex, all the fellowship, all the life of the mind in British culture, was had by them, and we’ve never seen their like since.

The problem with building a new Bohemia is that your ideas have to be good, your creativity has to be real, and that is all untestable as it happens: it is only in retrospect that we can see the legacy of Keynes and Woolf. The artistic overhang of Grant and Bell is not especially significant. There were more important artists of the era, with less interesting lives. But their Omega Workshops (a design house, making textiles and furniture, trying to give concrete visual expression to the group’s ideas) were influential, both in terms of the aesthetic they introduced, and the political statement they made, democratising the means of production, clawing back influence for artists rather than patrons.

We can say all that now, but it was not clear at the time, and they were as satirised as they were admired. The admiration would never have survived had the movement not had, for its engine, a set of genuine and original ideas. Contrast the YBAs, the Young British Artists of the nineties, who had as much noise around them – perhaps not as much shagging, certainly as much of a feeling of a gilded clique, but rather an empty set of founding principles: that meaning was dead, craft was dead, purity was dead, business was inseparable from art and money was indivisible from worth. It had a certain internal coherence, and it made perfect sense within the age, shot with postmodernism, and – in the nonsensical framing of the day – post-irony; but we can already see that it had no legacy. Nobody will be talking about Damien Hirst in 2050.

You also need a lot of money. Woolf famously said that, to write fiction, a woman needed money and a room of her own, and presumably to deliberately mislead, turned that into a Room of Her Own: money was obviously the important bit, rooms you can buy with money. And yet it was more than a practical consideration, even though there were plenty of practical things that could never have happened – the establishment of Charleston as a proto-commune – without it.

They were not, after all, the first artists to sexually experiment. William Morris, 50 years earlier, was much more radical, a true and pioneering believer in liberated female sexuality. Oscar Wilde, in the same period, made a much fuller philosophical account of homosexuality than Lytton Strachey ever did. The Bloomsbury set didn’t invent any of this, though arguably the polyamory was new, and invested it with glamour as a consequence of their class.

There was, then, and I’d say still, a peculiar national inability to disapprove of the things that posh people do. I went to Charleston as a teenager; it’s a fascinating cultural snapshot of class and rebellion. All the pride is in the painting and the memorabilia, intricately decorated mantelpieces, a fresco of a friendly dog; and yet it wouldn’t be charming, it wouldn’t be possible, it definitely wouldn’t have such a pretty garden, without the wealth that it seems almost blind to. Since it became a museum, the names of each room’s inhabitant have been painted over the doors by the trust; an ancient posh-o observed to me that they probably needed those to remember whom they were sleeping with.

I was really struck by the indulgence, the fondness of the remark: from a person who, if he found out his friends were polyamorous or his sister were sleeping with a heterodox economist, would have been scandalised. The social status of the group legitimised everything they did. Ultimately, this is why the experiment was unreplicable, because there was a contradiction at the heart of it: their very freeness was only allowable by the bourgeois conventions – that one admires one’s betters – that they explicitly rejected.

• This article was amended on 27 July 2015 to correct the spelling of straitjacket.