It was not the most edifying moment in David Cameron’s career. Towards the end of last year’s election campaign, he launched the Tories’ manifesto for small business, and suddenly tried to affect the bulgy-veined zeal common to American wrestlers, albeit with the diction of an Anglican vicar. The result was a camped-up tribute to the entrepreneurial spirit that was quickly edited into a single sentence, ready to go viral: “Taking a risk, having a punt, having a go, that pumps me up.”

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One year on, he has taken easily the biggest risk of his political career, and ended up looking strangely deflated. We know he will be gone by the next election, whether that falls in 2020 – or, in the scenario envisaged by some of the irate Tories who are already after his head, a lot earlier. Despite having managed to unexpectedly win an election outright, his government’s latest legislative programme amounts to precious little: as Michael Portillo elegantly put it two weeks ago: “After 23 years of careful thought about what they would like to do in power … the answer is nothing.”

If the UK votes to leave the EU, Cameron is obviously toast; if remain wins, for the remainder of his time he’ll be serially tormented by many of his MPs yelling about betrayal, and making the most of the Tories’ small majority.

On issues from disability benefits to trade union rights to schools, Downing Street is already littered with U-turns and tactical retreats. Meanwhile, Cameron’s former Tonto, Steve Hilton, insists that when it comes to Brexit, if the PM were “a member of the public or a backbench MP or a junior minister or even a cabinet minister, I’m certain he would be for leave. That’s who he is”.

Just to compound the confusion, Cameron now affects to be a fan of Sadiq Khan, paying tribute – with the kind of brazen nerve that these days costs parents over £30,000 a year – to the way that “in one generation someone who’s a proud Muslim … can become mayor of the greatest city on Earth”, something which apparently “says something about our country” (most notably, perhaps, the fact that millions of Britons wanted no part of a smear campaign to which the PM enthusiastically signed up).

More than ever, then, the questions buzz around the prime minister: who exactly is he? And what does he want?

Most political careers end in failure. But there is a particularly tragic aspect to Cameron’s decline, bound up with things much bigger than him and his party. As the rise of the malignant Donald Trump shows, post-Thatcher/Reagan conservatism – a matter of free markets, untrammelled trade and the idea that self-reliance will see most people right – is fast running out of road. As Aditya Chakrabortty pointed out in these pages this week, even the research department of the International Monetary Fund now seems to agree, drawing attention to rising inequality and the absence of sustainable growth.

A general unease with how western societies have developed explains not just the various political revolts now seizing no end of countries, but sporadic attempts at creating a new British Conservatism over the last decade. Indeed, with each annual Tory conference, there has seemed to come a new one. “Red Toryism”, “blue-collar conservatism”, the “Good Right”, the self-consciously ethical Tory project backed by Michael Gove – all of them focused to some extent on a need to reinvent politics, the Conservatives’ failure to speak to life as millions of people live it, and an economic model increasingly failing to provide security and certainty. But thanks chiefly to the prime minister’s lack of enduring interest, none has ever seemed to go anywhere.

What remains of any Cameron project? Empty entitlement, an appetite for tactics over strategy

The strange thing is, the questions they have half-grappled with are precisely the ones he told us he had come to answer. The other day I re-read the conference speech that helped him win the leadership in 2005 – a tour de force that was inevitably bigger on high-flown rhetoric than detail, but still promised a new kind of conservatism. “The shouting, finger-pointing, backbiting and point-scoring in the House of Commons – that’s all got to go,” he thundered.

There was talk of the aspects of everyday existence that post-Thatcher Tory politics had too often ignored: “To the new parent who worries about the air her kids will breathe, the state of the parks where they’ll play and the food that they put in their mouths, we’ll say, ‘Yes, the Conservative party understands that the quality of life matters as well as the quantity of money.’” Presumably thinking of junior doctors, teachers, council employees and the rest, he also focused on the fact that “public servants no longer think we’re on their side”.

The aim, he said, was to “look, feel, think and behave like a completely new organisation” – topped off the following year by his warning that too often in recent Tory history, “while parents worried about childcare, getting the kids to school, balancing work and family life, we were banging on about Europe”. A smirk at the absurdity of what has happened since is inevitable, but at the heart of this was quite a good idea: the “big society”, that attempt at pulling social concern away from the big state, and seizing on the opportunities for self-organisation offered by the Facebook age.

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The concept was dead by late 2012: as against the Tory fantasy that cuts would clear the way for some great flowering of voluntarism, it turned out – who knew? – that without grants, many charities would struggle. Out in the real world, meanwhile, there are thousands of social enterprises and creative councils (Labour, mostly) still just about carving out a social space between the centralised state and the market. Claiming credit for what they do is beyond even the prime minister’s chutzpah.

What remains of any Cameron project? Not much. Cameronism, if one can use such a word, seems mostly composed of empty entitlement, an appetite for tactics over strategy, and a lukewarm belief in some kind of continuity Thatcherism. Some latter-day Theresa May – even the woman herself, perhaps – could still take the stage at a Tory conference and warn them about the “nasty party” perception. Most of the north of England and nearly all the UK’s cities continue to present a political challenge the Tories cannot meet.

For sure, winning by default thanks to a knackered Labour party is much better than losing, but it does not detract from either a sense of slow decline, or the continuing Conservative quest for a politics suited to the 21st century. Cameron has addressed neither: whether he is sent on his way this summer or a few years afterwards, the sense will surely be of a strangely lonely figure, walking away with little more than the stale remains of his own ambition.