It doesn’t really matter who takes the reigns in a severely depleted Tory party, writes John Rentoul. The Labour leader’s biggest challenge will come from his deputy

Nigel Farage, the well-known political commentator, put his finger on it in the TV debate on Friday night: “The real leader of the Labour Party is here on the stage – at least she’s got some personality.”

Angela Rayner has grown in power since she was exonerated on the Conservative charge of tax-dodging. She used her renewed strength to put herself at the head of the Labour rebellion against Keir Starmer, which forced him to back down from the plan to stop Diane Abbott, Jeremy Corbyn’s ally, returning to the Commons as a Labour MP.

In the seven-way TV debate, Rayner was conspicuously loyal to Starmer. She even energetically denied that she was opposed to Britain’s nuclear weapons – one of the symbols of her ideological difference from the Labour leader.

Her denial is unconvincing. She claims to have voted against Trident in 2016, when parliament voted to build the next generation of nuclear-armed submarines, because she is in favour of multilateral disarmament. Getting rid of Britain’s nukes regardless of what other countries do is an unusual definition of multilateralism, but the point is that she is trying to support the party’s pro-nuclear line.

Her strategy is transparent: unity now and maybe a different position later. Starmer can hardly complain; it was how he won the leadership of the party, after all. But it does suggest that there might be trouble ahead.

I have it on good authority that the highest levels of the civil service now expect a large majority for Starmer and predict that it could turn out to be a big problem for him: “It means the internal opposition will be the one that matters, not the external enemies.”

This is not a surprising conclusion, if we survey the state of the Conservative Party and recall recent history. The Tories seem to be going through the rituals of an election campaign while thinking about how to fight the civil war afterwards. All the elements of Tory Corbynism that gave us Liz Truss as prime minister are still there, not far below the surface.

We can tick off all the beliefs that are a mirror image of the politics of the Socialist Campaign Group: The true path was betrayed from within. Tick. The establishment, including the media and the markets, conspired against us. Tick. The traitors are no different from the Other Side. Tick.

Thus the Torbynites accuse their opponents in the Conservative Party of being “social democrats”, and Truss herself bemoans their failure to overturn the “Blairite consensus”. Just as Corbynites accused mainstream Labour members of being Tories who had no interest in overturning Thatcherism.

To ensure that the Tory infighting after the election is really bloody, centrist One Nation Tories increasingly use the language of “hard right extremism” and even “fascism” about their fellow Tories.

The idea that Rishi Sunak might stay on as party leader after election defeat to try to stabilise the party now looks like a forlorn plan. Michael Howard was able to do that in 2005, and thus clear the way for David Cameron as his successor, because he had fought a competent campaign that slashed Tony Blair’s majority.

The Blair years are a guide to what might happen next. With the official opposition party incapacitated, Labour provided its own opposition. The fissure between Blairites and Brownites widened and became a settled feature of the landscape. The opposition to foundation hospitals, tuition fees, the Iraq war and 90-day detention came from Labour MPs. In each case, Brown signalled his doubts before siding with Blair at the last moment.

Rayner has already showed that she understands how this game works. One of the reasons Starmer took such a hard line on the selection of parliamentary candidates is that he knows that discipline will be hard to maintain if there are four times as many Labour MPs as there are ministerial posts available.

But no matter how many leadership favourites were parachuted into safe seats at the last moment, the centre of gravity of the new Parliamentary Labour Party is going to be to the left of Starmer.

And the new government is going to face challenges that will test the loyalty of even the most Blairite MPs. We had a foretaste of that in the seven-way TV debate when Rayner made a (Blairite) virtue of Labour’s “honesty” in refusing to promise to lift the two-child limit on benefits. We won’t promise anything without saying how it will be funded, she said.

The pressure to lift the two-child limit, which is inexorably increasing child poverty, will become intense the moment Labour has the power to do it. But the new government will have no money, and Rachel Reeves’s emergency Budget in September is likely to have to make cuts in public spending that the new model army of Labour MPs will find hard to accept.

Even Blair, who did not have to make cuts, provoked 47 Labour MPs to vote against his government in December 1997, just seven months after the election, when he cut lone-parent benefit. Gordon Brown, despite being chancellor of the exchequer, made sure that everyone knew that it was Blair’s cut and nothing to do with him.

It hardly matters, then, whether it will be Kemi Badenoch, Penny Mordaunt or Priti Patel who is leader of the official opposition this autumn. There may be so few Tory MPs that her troops will struggle to fill the benches on the speaker’s left.

The real leader of the opposition will be Angela Rayner, deputy prime minister – and she will be biding her time.