IF the Tories remained in power after the next general election – for the fifth time in a row – it would be a first for any party. If they then stayed in power right up until 2029, their 19-year stint would outstrip even that of Margaret Thatcher and John Major.

By then, Britain would feel to some like a one-party state.

But Labour still has a decent chance of toppling the Tories in 2024. The Prime Minister’s chronic mendacity is currently whacking the Tory brand, with Sir Keir Starmer now 12 points ahead of his rival in the polls and his party 10 points clear of the Tories. Boris Johnson looks likely to be defenestrated at some point. Labour MPs should be feeling chipper.

But there are signs of Labour nerves about a new Conservative leader – and with good reason. Yes, this government is manifestly unfit; yes, the rule-breaking parties and the sleaze and the Brexit mess and the apparent indifference to food bank queues should do for them, but the Tory party is nothing if not resilient.

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As if possessed of its own Tardis, it keeps regenerating, producing one new leader after another to receive the Prime Ministerial baton. The next incarnation of Dr Blue is likely to be in the form of Liz Truss or Rishi Sunak, and that’s what’s bugging Keir Starmer: how to stop a future new Tory leader from setting the dial back to zero, clearing out old staff and behaving as if, having done a spring clean, they are offering voters something new and fresh that’s nothing to do with Boris Johnson.

Such has been the English propensity to elect Conservatives – mystifying as it may be to Scottish observers – that the party are pushing at an open door. If they can successfully regain voter trust post-Johnson and cut a few taxes just before the poll, then all the gilded splendours of a renovated Downing Street could be theirs for yet another five years.

Starmer doesn’t intend to let them get away with that and used several of his questions in the House of Commons this week to tie ministers to the Prime Minister’s wrongdoing: “How much damage are the Prime Minister and his cabinet prepared to do to save his skin?”, he thundered; and: “Every day his cabinet fail to speak out, they become more and more complicit.”

This followed an apparent attempt by Liz Truss to distance herself from partygate by calling for a “change in culture”.

But the Labour leader will need more than a charge of guilt-by-association against an incoming Tory leader to swing a future election his way. If he frames a Labour vote as a protest vote, then heartbreak awaits. As in 1997, voters must see Labour as an attractive, desirable alternative to the Tories and in particular as trustworthy on the economy.

It’s only a few months since Keir Starmer was trailing Boris Johnson rather badly in the polls. Since then, voters have rediscovered their affection for Starmer, but Labour remains a long way behind the Tories when it comes to people’s perception of which party is better equipped to manage the economy.

Ironic, you might say, given that this is a widely discredited myth – Labour governments are better at handling recessions and are more consistent in their economic performance than Tory ones. But what matters here is the perception. Tory propaganda blaming Labour for profligate spending after the financial crash, coupled with Jeremy Corbyn’s leadership of Labour, damaged Labour’s carefully built reputation for what Gordon Brown called “prudence”.

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Labour are currently making a lot of their call to cut VAT on fuel bills to help with the cost-of-living crisis while the government sits on its hands; if Rishi Sunak acts, then Labour can loudly take the credit. Meanwhile, cool heads and calm voices are in charge in the Labour policy team. Shadow chancellor Rachel Reeves has committed a Labour government to keeping a tight rein on borrowing, ensuring tax revenues cover daily spending and ensuring public debt falls as a share of national income, though infrastructure spending would be more generous than under the Conservatives.

So Labour too are metamorphosing. You expect that of opposition parties, but long-standing governments usually don’t have the same luxury. They linger in the public eye, getting tired and running out of ideas (exhibit one: the SNP).

The Tories at Westminster have been spared that fate, ironically, by Brexit. The Brexit vote looked as if it was destroying them. It went off with a bang, throwing the party into disarray, but when the pieces came back to earth, the party looked very different indeed – new voters, new MPs and a new and unpredictable leader. It gave them a new lease of life just after the beleaguered and seemingly terminal May years.

Yes, the same party has ostensibly been in power for the last 12 years, but really it’s been two rather different parties: the socially liberal husky huggers of the Cameron era whose sales pitch was to wrestle down the national debt (saddling the country with an overlong period of austerity); and the populist post-Brexit party of Boris Johnson, which moved sharply to the right on social issues and left on the economy.

What comes next will be another iteration entirely, but still wearing the blue rosette.

So Labour needs to start whipping up some enthusiasm for a real change, instead of this game of Tory musical chairs. Keir Starmer has been pitiless over the Downing Street Christmas parties, going after Boris Johnson like a lawyerly piranha fish, but he and his ministers need to do so much more. Labour needs to be the government-in-waiting, not Truss and Sunak. They need to define how the country will become fairer while maintaining prosperity. They must sound not only trustworthy and compassionate – Starmer’s got that covered – but economically competent. Soon, the government’s overdue White Paper on “levelling up” will come out: Labour must be ready. What they offer must be sharper, cleverer, more credible and more exciting. That’s how 2024 will be decided, not on which of Mr Johnson’s many lies can be proven. By 2024, he could well be a fast-receding speck in the rearview mirror.

There is after all so much resting on the 2024 election, not least in Scotland, where the implications of a Labour victory in 2024 are obvious (a Labour government in Westminster could well erode support for independence).

In parliament this week, the superficially bullish Prime Minister told Mr Starmer he needed to “up his game”. It was a defensive remark, in the face of the Labour leader’s prosecutorial attack, but in a sense the Prime Minister was right. At the moment, in spite of this lame government’s travails, it would be risky to bet on a Labour victory in 2024. It’s still the Tories, not Labour, who set the political agenda. That must change or the Tories could cling on to government for years to come.

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