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In the autumn of 1983, Austin Mitchell published an obituary of the Labour party in book form. Mitchell had been elected as MP for Great Grimsby in the by-election held in 1977 on the death of Foreign Secretary Tony Crosland. Labour just held on in that by-election – by 520 votes – in a narrow victory that after the shock of Crosland’s untimely death came as one of the last pieces of good news Labour was to receive for many a year. Jim Callaghan then missed his opportunity to hold an election in 1978, when he might well have defeated Margaret Thatcher and the Conservatives, ensuring that the 1980s would perhaps have unfolded quite differently. As it is, Labour lost office in 1979 and Mitchell was there as an eyewitness in the Commons during the party’s subsequent descent from self-proclaimed “natural party of government” to national bad joke.

Mitchell’s book (Four Years in the Death of the Labour party) is a fascinating read, a lost time capsule rediscovered, in which he recounts how the left and parts of the trade union movement foisted an unsuitable leader on Labour in opposition, leading to a split with the moderates and the creation of the SDP by senior Labour figures and then a crushing defeat that gave Thatcher her first landslide in 1983.

The use of the word death in relation to Labour was clearly more than just a publisher’s bid to make a book about politicians seem more exciting. It was no exaggeration to say that Labour then looked doomed. Anyone who was there will tell you that the imminent extinction of the party was regularly discussed, with the SDP and Liberal party splitting the anti-Tory vote, letting Thatcher through the middle. As a broken old relic of the industrialised era, dependent on the unions and out of touch with the emerging changes in British society, Labour looked finished

But it did not happen. Labour did not die. It regenerated itself and 14 years after the defeat in 1983 it somehow delivered the worst Tory defeat since the end of the Second World War.

How did Labour dodge the knackers yard of history? In part it was down to the quality of personnel. Even during that period, when Michael Foot was leader, a heavyweight Denis Healey was a leading player, alongside figures such as Roy Hattersley and John Smith. Then a new generation arrived in parliament in 1983. That is the year Tony Blair and Gordon Brown became MPs and began their ascent. Blair in particular became attuned to the consumerist zeitgeist, turning himself and his party into a Tory destroying vote-machine, an innovation which earned him the hatred of the hard left which secretly prefers defeat to victory because it produces the whiff of burning martyr.

Labour was also helped by the existence of a deep ancestral and tribal loyalty on the part of core voters that the SDP could never match. The rival outfit started well but was easily satirised as a middle class cliché, a nice but ineffective party for the Volvo-driving and avocado-eating classes. It later tried an alliance with the liberals, which blunted its original appeal, and what emerged in the end was the Liberal Democrats, a knit-your-own yoghurt third party who still split the anti-Tory vote and got nowhere near government until 2010 in coalition.

Labour at its low-point also retained a so-called Celtic redoubt in the form of a robust presence in Scotland and Wales. It had great residual strength. Labour could lose in England and still retreat north and west to begin its fightback from there, which is what it duly did.

The experience of the 1980s and subsequent resurgence in the 1990s induces wariness on the part of anyone tempted to predict the end of Labour now. But just because Labour has survived a previous brush with mortality does not mean it will survive in perpetuity, or at least not in any form that gives it a hope of keeping British politics competitive by offering a credible non-socialist non-Tory alternative to voters.

Indeed, the events of the last five days – which one might term five days in the death of the Labour party – have provided more proof that Labour may already be a former political party. Philip Collins of the Times said that he had never before witnessed such staggering incompetence in politics and it is impossible to better that verdict.

The Conservatives on Friday issued a press release detailing the travails of their opponents, and for once it is a press release worth drawing on.

On Monday, doomed leader Jeremy Corbyn was going to end Labour’s attachment to “free movement” of people in the EU, as a way of reducing immigration and signalling a new post-referendum policy. By Tuesday he had reversed his u-turn, and then continued to go round in circles all day. I am paid to follow these things but cannot explain where the Labour leadership ended up.

Tuesday and Wednesday were spent defending the strikers bringing misery to millions of commuters hit by rail strikes. Worse, even though there is wide agreement that the state-run behemoth the NHS is suffering one of its winter crises, Corbyn could make little of it in his encounter with Theresa May at PMQs in the Commons.

On Thursday, Corbyn’s spokesman then decided to condemn the deployment of British troops  to defend Estonia as part of the UK’s commitment to Nato.

On Friday, one of the party’s stars – Tristram Hunt – announced that he is resigning as an MP to become a museum director (perhaps Labour should be in it?) and Labour now faces a by-election in Stoke-on-Trent Central, in which it will find it difficult to hold off UKIP.

And that was supposed to be the week in which Corbyn relaunched. What’s he planning for next week? Will he be strapped onto a rocket and fired into outer space?

There are plenty of Conservatives who think that this is tremendous news for their party and for Britain because it offers the prospect of endless Tory rule. Perhaps it does in the short-term, with Labour done in Scotland, in trouble in Wales, vulnerable to UKIP in Labour parts of the North, and nowhere in the South or Midlands, where Mrs May has formed a strong connection with voters.

Yet the death of Labour is dangerous, for two simple reasons, one connected to the future existence or otherwise of the UK and the other connected to the serious damage being done to Britain’s democratic fabric.

In Scotland, Labour was a bulwark of the Union until it decided to blow itself up by delivering devolution that let in the SNP. Now Scottish Labour has had it.

Worse than the threat to the Union, because many English voters would probably not give much of a stuff if Scotland went, it would at least end the high-pitched whining sound emanating from the SNP, or stop it reaching England, is what the collapse of UK Labour means elsewhere.

The frequently derided two party system has served Britain well, certainly when one compares the British experience in the 20th century to that on the European mainland. As Kenneth Baker, Lord Baker, puts it: the British two party system was highly successful because it kept out the extremists. On the right it denied room to the fascists, led by Mosley, that is the old man, not his son destroying the free press. The far right parties that followed never got fully established or won parliamentary seats. On the left it kept out the hard left and compelled social democrats in Labour to win over a portion of the conservative or non-aligned vote to gain power and get anything leftish done.

That two party system is now in a state of advanced decay, introducing scope for the emergence of new forces and new anti-politics populist parties promising simple solutions which might look exciting at first. Sufficient numbers of Americans thought something similar about Donald Trump, enough of them to make him President. It means an electoral system designed to guard against the election of a demagogue failed and a snake oil salesman enters the Oval Office next week.

Moderate conservatives and moderate centre-leftists in the UK should be worried and alert. Any British smugness about Trump, and confidence that the election of a populist leader or party would simply not happen here in an ancient parliamentary system, looks misplaced when one half of the long-established party system is a goner.