In the historian John Bew’s absorbing, riveting new life of Clement Attlee (Citizen Clem, riverrun £30) he explains how the future Labour leader went from being a young imperialist Tory – a default position considering his affluent background – into a full-blown socialist. It was a serious journey (dread modern usage of word) that makes the plastic posturing of the tinpot Trots and hypnotised millennial Corbynistas today look just silly.

Incidentally, I described Citizen Clem as a riveting book. If you find the notion of anything connected to Attlee being remotely riveting somewhat ridiculous, then Bew’s work should make you think again. Labour’s biggest election winner, until Tony Blair, may have been regarded as inefficiently dynamic in terms of public relations, even by the reserved standards of the 1940s, but anyone who was injured seriously at Gallipoli and then served on the Western Front in 1918 would be perfectly justified in concluding that he had had more than enough excitement and exuberance for one life. Later, Churchill occasionally mocked the modest Major Attlee, his Labour deputy in the 1940-45 coalition, but would not tolerate hearing it from others:

“Mr Attlee is a great patriot,” Churchill told a Tory MP visiting Chartwell. “Don’t you dare call him ‘silly old Attlee’ at Chartwell or you won’t be invited again.”

Attlee was a great patriot; of that there is no doubt. One wonders what he would have made of Jeremy Corbyn, considering that Attlee was a muscular multilateralist and a realist about war and aggression, someone who had experienced it on the front-line. In office after 1945 he took the right action that secured a nuclear deterrent for Britain and during the period of the wartime coalition he was a useful counterpoint to the much more erratic Churchill. Attlee the patriot accepted much of the British system – its constitution and traditions – while trying to dismantle the economic Establishment via nationalisation and taxing wealth like mad. His reputation, resting on the creation of the NHS, is long overdue a proper reexamination, and Bew has done his subject justice.

But for all that I admire the work of an emerging great historian engaged in an act of scholarly rehabilitation, there is no getting away from it. Attlee was a socialist. And it cannot be stressed too often that Socialism is a very bad idea indeed.

There are several forms of it, of course. The most extreme is Communism, with its record of mass murder and a list of victims stretching into the many tens of millions.

Then there is what used to be termed parliamentary Socialism, or at times social democracy, which completely rejects Communist tyranny every bit as forcefully as conservatives do. The parallel in the US is with the Democrat Cold War hawks who were on the Soviet Union’s case. Domestically, the mainstream British Labour party eventually abandoned the “S” word, after repeated prompts from the voters of England, while pursuing socialist ends (equality) by milking the market.

The rejection of Toryism for mainstream English Labour people is often cultural as much as anything. The Tories are the men in red trousers shouting at the rugby. They are heartless bosses and bad bankers in sports cars. The powerful myth of Tory sheer awfulness persists, and now Theresa May will have her go at repudiating it.

This creates a strange set of circumstances. The mainstream moderate left that recoils from the Tories is a very strong presence in British life that is now without proper representation at Westminster, other than from a group of persecuted moderate MPs. But the moderates are also without what might be termed a coherent agenda beyond removing Corbyn. What would a new Blair say now? The fact there is no new, charismatic, mainstream successor running in this leadership election simply demonstrates again that globalisation plus the financial crisis has left the mainstream left looking rather stuffed.

The disreputable British far left of the Corbynistas sits right between those two approaches, between communism and parliamentary socialism. Leeching off the latter, and slyly excusing the former.

There is, of course, another more vague and part-time category. Let us call it dinner party socialism. Some of my very favourite people are dinner party socialists and you should hear what they call those of us who voted for Brexit. The part-time socialists quite often send their offspring to private schools while explaining that even if proper socialism has not yet been attained we should always at least strive for it in our hearts…

No we should not. If you want a picture of what it looks like when implemented, consider the horror that is contemporary Venezuela. Until relatively recently it was the Corbynite exemplar, the laboratory where true socialism was being invented. It is now in economic ruins, run by a tyrannical government presiding over enormous poverty and facing vast public demonstrations. The idea that there is a nice, cuddly version of this mad, controlling experiment is one of the most crippling delusions of the last century. It isn’t there.

And the reason why not can be explained with reference to the biggest mistake made by Attlee and his generation of Labour politicians, scarred by the memories of the Great Crash and the slump that followed, and by two wars.

Why was Attlee a socialist? His was the socialism of the Edwardian industrial East End of London where he had volunteered in a boys’ club. To say that times were hard for people in manual labour fearing illness or ruin is an understatement. In the City a few miles away was the most powerful financial centre the world had ever seen, with gilded banking halls and the government’s brokers in the money markets wearing silk top hats. The East End teemed with life, too much of it nasty, brutish and short. This was replicated in all the great industrial centres of imperial Britain.

While the industrial revolution had been a force for good, the attempts by Liberal and Tory politicians and philanthropists to ameliorate the side-effects of rapid industrialisation, and to improve the social conditions of the poorest, had not been nearly successful enough. Attlee became convinced like many of his generation that the only answer lay in the government taking control of industry, planning production and handing out the proceeds more equally. The new Jerusalem would be state-owned and built in England’s smog-ridden industrial heartlands.

His rejection of the market and its mechanisms was a terrible error that ended up being extremely painful to rectify in the 1980s. One of the main revelations of the Victorian era had been that open markets worked and widened prosperity. Free trade and the abandonment of protection made Britain the dominant economic power on earth. It paid for infrastructure and a national flowering, even if not all were included fast enough. That extraordinary open system – in which capital washed in and out of the country unimpeded – was ended by the First World War, after which the City, until then the centre of the international system, went into a decline, which only properly began to be reversed in the late 1950s.

Attlee in 1945 was operating in denial of the obvious. The market properly harnessed is a marvel. The incentives provided by it through profit are unmatchable, that is if you want innovation and prosperity. Markets are really simply about needs and desires being met, by a process involving millions of decisions by individuals which culminate for most of us in rival supermarkets, constantly improving cars, much better food, cheaper flights, leisure, choice and travel. Try and imagine instead how good a Corbyn-run single national airline or supermarket chain would be.

In 1945, Labour not only nationalised industry. It accompanied that decision with another utterly duff manoeuvre. Unfortunately they chose a controlled and closed economic model, when everything that has happened in finance and trade since the 1960s demonstrates that openness and competition were and are key. This applied to money most of all. Unlike in Germany, which was awash with dollars and open thanks to its pioneering post-1945 economics minister Ludwig Erhard, in the UK we persisted with tight exchange controls after the Second World War to protect the currency. It was not until 1979 that money could flow in an out again freely, from the tourist going on holiday to Spain to the British business making an investment in Seattle, or the New York investor betting on London. Britain reopened to the world in that period, and soon after the government got out of the business of owning industry.

In the face of this Jeremy Corbyn goes on reciting ancient mantras, his mind closed, seeking not to harness or reform the market, but to smash it to pieces.

That is way worse than him being merely unelectable. On economics, the state and something as powerful as what makes human beings make, sell and consume each others products and services, he is utterly clueless. Such is the sorry state of mainstream Labour that this appalling situation generally cannot be mentioned much, because of the views of much of the membership. That means pretending it is just about his lack of televisual appeal and colluding in a myth that Corbyn’s heart is in the right place when it is not, that the goal is ultimately Socialism and it’s just a question of pace. It means ignoring the lessons of seventy years of history and more.