There’s a leadership battle. The party is torn between left and right. A candidate considered unelectable unexpectedly wins, creating an ideological rift. The knives come out, with fears the party will never win an election again. But the new leader sticks to their guns. They doggedly push through, and cause the biggest ideological shift in the party’s history.

The parallels between Margaret Thatcher’s election as Tory leader in 1975, championing the New Right, and Jeremy Corbyn’s unashamedly socialist takeover of Labour 40 years on, are striking.

Thatcher was the figurehead for a small neo-liberal gang, seen as having little potential traction with the wider electorate, even by her own party. I once interviewed Sir Tim Bell, Thatcher’s advisor for the 1979 election, asking him whether this takeover of the Conservative party wasn't a kind of right-wing Trotskyite coup. He said he'd never thought of it like that before, but agreed. A small group of fiercely intellectual ideologues had hijacked a floundering Tory party, bringing about seismic political change few in Britain realised was coming.

Like Corbyn’s grassroots supporters within the Labour Party, these right-wing Trotskyites were outsiders who felt they had no voice within the Westminster elite. And just like Blair and Brown do, the Tory grandees distrusted and looked down upon these revolutionaries. The New Right weren’t from Eton, they were lower middle-class and state-educated (like Thatcher), or Jewish (like Keith Joseph), or worst of all to the establishment, immigrant and intellectual (like their guru, the IEA’s Arthur Seldon). They weren’t part of the club, so they took over the club instead, and rewrote the rules.

Yet right up to the 1979 election, many in the Conservative party continued to see Thatcher as a walking electoral disaster. One commentator, Woodrow Wyatt, who went on to become a Thatcherite loyalist when she won, warned that she would take her party in “an extremist, class-conscious, right wing direction” that would prevent the Tories winning for a decade.

Her voice was too high and shrill. Her clothes all wrong. Just as Corbyn is lampooned for having a jumper and a beard. Thatcher refused to sugar coat her message. She was a “conviction politician”. She believed what she said, as Corbyn does.

Jeremy Corbyn meets Edinburgh Fringe Festival comedy act Margaret Thatcher Queen of Soho while he campaigns in Scotland on August 14, 2015 (Mark Runnacles/Getty Images)

Thatcher had the last laugh on her detractors, just as Corbyn threatens to today. The Tory grandees who plotted to remove her, fearful she’d lose in 1979, were summarily shown the door. Just as the Blairite robots will be: dull, auto-idea throwbacks to the focus-grouped Nineties, who are beginning to realise they should have understood the mechanics of his popularity earlier, rather than do everything in their power to stop him.

The past is a comforting place, but it’s the Blairites who seem to be living there, rather than Corbyn. People who for so long believed wearing a business suit immediately conferred electoral credibility.

They seem shell-shocked by Corbynmania, but really theirs is a failure to understand that politics in Britain is being reconfigured by a bewildering array of forces: austerity, Cameron, Ukip, the SNP, immigration and inequality, to name a few. Reading off a fading Xeroxed script faxed to them in 1993 by Peter Mandelson just ain’t going to cut it anymore.

Margaret Thatcher - a life in politics Show all 9 1 /9 Margaret Thatcher - a life in politics Margaret Thatcher - a life in politics Margaret Thatcher and politics 1950: British prime minister Margaret Thatcher, then Miss Margaret Roberts, attending a garden party at Buckingham Palace, as a Conservative MP. Margaret Thatcher - a life in politics Margaret Thatcher and politics Margaret Roberts, later Thatcher, the youngest candidate in the Conservative Party, plans her election campaign. Margaret Thatcher - a life in politics Margaret Thatcher and politics 3rd June 1975: British conservative politician, Margaret Thatcher, with William Whitelaw and Peter Kirk, at a referendum conference on Europe. Margaret Thatcher - a life in politics Margaret Thatcher and politics Margaret Thatcher, accompanied by her husband Denis (1915 - 2003) and children Carol and Mark, on election night when she led the Conservative Party to victory in the British General Election. Margaret Thatcher - a life in politics Margaret Thatcher and politics 1982: British prime minister Margaret Thatcher, American president Ronald Reagan (left) and US Secretary of State Alexander Haig (centre) outside Number 10, Downing Street during Reagan's state visit to London. The new UK/USA 'Special Relationship' was founded on the rapport between the two leaders. Margaret Thatcher - a life in politics Margaret Thatcher and politics 14th January 1982: British Prime Minister, Margaret Thatcher, with husband Denis (1915 - 2003) and children Mark and Carol. Margaret Thatcher - a life in politics Margaret Thatcher and politics Margaret Thatcher celebrates on election night in 1987 Margaret Thatcher - a life in politics Margaret Thatcher and politics British Prime Minister Margaret Thatcher flanked by her husband Denis, addresses the press, 28 November 1990 for the last time in front of 10 Downing Street in London prior to hand her resignation as prime minister to Queen Elizabeth II. Margaret Thatcher - a life in politics Margaret Thatcher and politics Margaret Thatcher waves to the press at her home, after leaving Cromwell Hospital on November 1, 2010

Let me declare a non-interest. I don’t belong to the Labour Party, nor do I have an interest in any one candidate winning over another. But from an outsider’s point of view, it seems to me that the anti-Corbyn machine has massively oversimplified the complex nature of his rise. Tony Blair held up his hands in the Guardian this week saying he didn’t understand politics anymore, so bewildered was he by Labour’s rush to elect Corbyn. Miliband, he said, had simply not been enough of “one thing or another”.

In translation, this means: “not enough like me, Tony”. Or… not socialist enough. Well, Corbyn could never be accused of that.

But I think Corbyn could yet have a surprise in store for both Labour naysayers and, more interestingly, the Tories. I'm talking about his potential appeal to, wait for it, middle Britain.

Unlike his rivals, Corbyn has three big things going for him that crucially count outside London: 1) he’s hated by the London party machine of spin and bullshit (that’s conveniently hated by everyone outside London); 2) he sticks to his values (regardless of whether you agree with them – and Home Counties one nation Tories respect that as much as Labour activists do); 3) he’s the underdog. Never underestimate an underdog.

So could Telegraph readers end up going for him in the same seemingly inexplicable way life-long Labour supporters voted for Thatcher in 1979? Stranger things have happened at sea. The dangerous thing for the Tories is not so much that he genuinely believes what he says, but what he says might not necessarily count against him.

In Andy Beckett’s fascinating social history of early 1980s Britain, Promised You A Miracle, London’s loony left GLC run by Ken Livingstone espoused bonkers policies such as gay marriage, cycle lanes, pollution-free zones, the teaching of multicultural diversity in schools, and affordable social housing. What madness! Forty years on, David Cameron endorses pretty much everything once considered a far-left fantasy, as a marker of modern, tolerant Britain.