The polls show historic defeat could be on the cards for Corbyn, but how historic? The Sun predicted a grisly end for the party

The latest opinion polls show that Jeremy Corbyn’s Labour is facing a general election defeat on the scale of Michael Foot’s 1983 loss to Margaret Thatcher when Labour was reduced to just 209 MPs – its lowest total in the second half of the 20th century.

During that campaign, one of Thatcher’s own cabinet ministers, Francis Pym, warned of the danger of an “elective dictatorship” inherent in landslide victories.

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When she won her 144-seat majority – the largest since 1945 – Thatcher immediately sacked Pym but that didn’t stop her launching the same “elective dictatorship” charge against Tony Blair when his 1997 victory eclipsed her own triumph and reduced the Conservative party to a rump of just 165 MPs.

It took both Labour and the Tories more than 13 years to recover from these historic defeats and regain the trust of the voters to put them back in office again.

Will it happen again this time? Will Theresa May’s snap election enable the Tories to drive into Labour’s heartlands in the Midlands and the north of England in a way not seen since that 1983 Thatcher victory? Will May in the process really be able to “kill off” Labour as the Sun newspaper predicted on Wednesday?

David Butler and Dennis Kavanagh in their authoritative study, The British General Election of 1983, concluded that 1983 saw “a spectacular retreat in the working class from Labour, even more so than in 1979”. Only 38% of manual workers and 39% of trade unionists voted Labour while 32% of trade unionists voted Conservative .

Critically Labour lost the support of the C2 social class – working-class car owners, buying their own homes and employed in the private sector – who voted 47% to 26% in favour of the Conservatives.

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They had voted Labour since 1945 and their defection delivered seats in northern England and the Midlands such as Bradford North, Dewsbury, Halifax, Hyndburn, Nottingham East and York to the Conservatives – often for the first time. In London, even John McDonnell’s current seat of Hayes and Harlington, which had been Labour since its creation in 1950, went Conservative.

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Corbyn’s Labour is now in danger of enduring the same fate, if the current opinion polls prove to be even broadly accurate. They suggest that May could secure a 44% share of the vote, comparable to Thatcher’s 42% in 1983, while Corbyn may poll even less than Michael Foot’s 28% share of the vote.

But the really worrying factor for the future of Labour is that the most recent polling data shows that the party has once again lost the support of that crucial C2 skilled working class section of the electorate.

Facebook Twitter Pinterest Michael Foot. Photograph: John Downing/Getty Images

According to the Guardian/ICM polling data going into the 2015 general election, Ed Miliband enjoyed the support of C2 voters by a margin of 45% to 25% over the Conservatives. This week’s polling data shows that Labour has lost its support among this crucial section of the working class, with 42% of them saying they will now vote Conservative and only 29% intending to vote Labour.

The current overall polling figures imply a 7% swing to the Conservatives, which could see Labour’s 229 MPs reduced to just 165 and the Tories gaining 66 seats to deliver a majority of more than 140 seats.

A swing on this scale could see Labour seats such as Oldham East and Saddleworth, Workington, Mansfield and Dudley North fall to the Tories. Even heartlands such as Peter Mandelson’s one-time seat of Hartlepool, Bolton North East, Hyndburn, Chorley, Bishop Auckland, and Leeds North East are vulnerable on a swing on this scale.

If, as expected, the polls narrow during the campaign, and May wins with a more modest 4% swing from Labour to the Conservatives, the parliamentary Labour party could still be reduced to a historic low of 195 MPs.

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The Conservatives would gain a more modest 39 seats – including Darlington, Clwyd South, Wakefield, Birmingham Northfield and even veteran Labour MP David Winnick’s seat of Walsall North – and a Tory majority of around 90. In London, Sadiq Khan’s old Tooting seat would also be lost.

Even if Corbyn is able to limit the Tory victory to a swing of only 2% and a majority for May of around 40, that would still see the loss of 15 Labour seats such as Chester, Halifax, Barrow and Furness, Dewsbury and Wolverhampton South West in the north of England and Midlands.

But none of these scenarios imply the total destruction of the Labour party in the Commons. One of Thatcher’s Downing Street aides, Tim Flesher, in a post-election note discussing the psephology of the 1983 election, told her: “Unless Labour falls apart it will, as you put it in the election campaign, not die because it has over 100 seats which it will keep in virtually all foreseeable electoral circumstances.”

That remains true today. Even if May matched Blair’s historic 1997 achievement of a 10% swing it would still leave Labour with a bedrock of 142 MPs. But while Labour may not face electoral annihilation, it would no longer be an effective national political force. It would be left a “zombie party” about as far from Harold Wilson’s boast of being “the natural party of government” as possible.