Back in 1996, a young Tony Blair told me at the end of an interview: “You really don’t have to worry about Jeremy Corbyn suddenly taking over — I know everything that’s going on in his constituency party.”

The boast of the then Opposition leader came sharply back to mind this week as a roomful of Liberal Democrats sang “Tony Blair can f*** off and die” at their conference, and the very Left-winger he once claimed to have under lock and key will get the chance to bury the Blair legacy even deeper.

At 11.45am on Saturday, barring a bigger surprise than both the Brexit vote and the 2015 exit poll combined, Jeremy Corbyn will be re-elected as leader of the Labour Party, probably with an even bigger mandate.

It is the defining event of the autumn conference season. Already, Tim Farron has galloped towards the vacant centre ground in anticipation. Theresa May is honing her campaign to woo the “working poor”, voters earning £16,000 to £21,000 whom she believes are delaminating from Labour because of Mr Corbyn’s perceived lack of patriotism.

As for Labour, it faces the prospect of months and probably years of internal conflict as Mr Corbyn and his enemies wrestle for control of the party’s internal levers. “It will be a continuing war of attrition,” said one MP grimly.

“We have got to put the band back together,” pleaded deputy leader Tom Watson just before yesterday’s marathon National Executive Committee meeting avoided a debate on his proposals to recalibrate the way future leaders and shadow cabinet members are chosen. But will the ensemble in Liverpool be playing The Beatles’ Come Together — or Frankie Goes to Hollywood’s bleak anthem, Two Tribes?

Mr Corbyn will be channelling Paul McCartney in his victory address, which allies say will be laden with olive branches. Over the next few days, they say, he will be “reaching out” to Labour MPs who walked out of the shadow cabinet in the summer, offering them “a new settlement”. They say a “significant number” of former frontbenchers have already signalled privately that they want to come back, enough to form a fully manned shadow cabinet in a reshuffle next month.

But the unity he offers comes at a price. For the Corbynites, the leadership contest has been advantageous because it unlocked an opportunity to make policy announcements that form the beginning of a “substantial platform”. Mr Corbyn peppered his summer campaign with pledges that would never have got through the old shadow cabinet without heated debate, including a promise of half a million extra council homes, nationalising the railways and cutting fares by up to 10 per cent, and a £500 billion investment strategy in the green economy. Mr Corbyn’s new settlement, in other words, sounds very much on his terms. The irony is that the old shadow cabinet, before the attempted coup against him, actually contained more centrist Labour MPs than Corbynites. And this radical shift cannot easily be reversed, because Left-wingers like Diane Abbott and Angela Rayner, who filled the gaps after the mass resignations, will cling hard to their promotions. “Jeremy is going to have to appoint loyalists to the big briefs,” says one Labour MP.

The Corbynites’ trump card is their leader’s mandate from the party membership, which a dissident MP interprets sourly as “their mandate to kick the shit out anybody who disagrees”. Certainly, the drumbeat of deselections has increased, with MPs such as Walthamstow’s Stella Creasy stalked by Momentum.

Also rising is the sense of foreboding at party HQ that Mr Corbyn will get the NEC to start a purge of officials. John McDonnell, the acid-tongued John Lennon to Mr Corbyn’s McCartney, has already clashed publicly with Labour general secretary Iain McNicol and accused officials of a “rigged purge” of Left-wingers.

Even Mr Watson, the elected deputy leader, would probably be facing a challenge, say MPs, but for the inability of the Corbynites to muster 50 names with which to trigger moves to oust him.

Some trace the current divisions to the very earliest days of Labour, when syndicalists questioned the need for parliamentary representation to achieve socialist change, with trade unionist Noah Ablett asking: “Why cross the river to fill the pail?” Mr Corbyn, they claim, belongs to a tradition that has always preferred the purity of direct action and protest to the messy compromises of elected power. The Labour leader’s supporters retort that his 30 years in Parliament disprove the idea.

Can anything bring the two tribes together? Probably not, though Mr Watson believes that shadow cabinet elections — where MPs pick the members and the leader allocates portfolios — would help patch up the Parliamentary Labour Party. Mr Corbyn is open to the idea of “an element” of elections but only as part of a wider review of internal democracy.

At the heart of Mr Corbyn’s version of internal democracy is the principle of one member, one vote — the system that put him into power.

It is striking that in all his reforms to create New Labour, Tony Blair never messed with either the leadership electoral college or the shadow cabinet elections. He instinctively knew that to change either would risk toppling the fine balance between the constituent parts of the Labour Party, unleashing unstoppable and chaotic forces.

Incidentally, that boastful-sounding quote from Mr Blair in 1996, which attempted to reassure middle England that New Labour would not revert back to the bad old days of 1980s militancy if voters trusted it with power, did not appear in the printed interview. Why? Because Jeremy Corbyn was such a marginal figure at the time that the idea of him taking over anything sounded ridiculous. But make no mistake: Labour’s leader is deadly serious about getting his own way from now on.