Kemi Badenoch could be forgiven for believing she had the perfect strategy to trip up Andy Burnham at their first PMQs clash.

The day before, our new Prime Minister had stood at the despatch box for more than three hours to be grilled by MPs – primarily nervous ones from his own party – over everything from the state of Britain's high streets to soaring energy prices.

And one eager-eyed Tory researcher had spotted an incriminating thing. Not once had Burnham rejected an opportunity to spend more public money.

So the attack line was duly set. Warning of the ructions in the bond markets, Badenoch chided Burnham as a 'spendthrift Prime Minister' who 'wants to say yes to everyone' and is wedded to 'the same old Labour politics of tax and spend'.

It seemed a good strategy – and the Leader of the Opposition prosecuted it with her usual verve.

Except there was one problem. Andy Burnham is indeed a spendthrift. He does enjoy saying yes to everyone. He most definitely is, at heart, an old-school tax-and-spend socialist. And he doesn't care who knows it.

For the past 30 years, Labour leaders have proven successful primarily when they have managed to convince people they are something they're not.

Tony Blair won three elections by pretending not to be a leader of the Labour Party at all. Keir Starmer secured brief popularity by posing as the son of an Oxted toolmaker – and watched his fortunes implode when the country swiftly twigged he really was another ultra-liberal human rights lawyer.

Andy Burnham is adopting a markedly different approach. The traditional, Northern, class-oriented branding he deployed so effectively in his campaign for the Makerfield by-election wasn't a one-off. It represents the template he will use to govern the country, and the basis of his pitch for the general election that is almost certain to be called next year.

Given the extent to which an ability to project 'change' represents in the currency of modern politics, many Westminster observers have been surprised by Burnham's first Commons appearances since securing the premiership.

In particular his full-frontal attack on Thatcherism – 'the legacy of which, I have to say to her, we are still struggling to reverse' – and his unashamed embrace of greater state ownership and control.

The truth is his team genuinely believe that approach will pay political dividends.

First, they are intent on shoring up his party's Left flank, and securing it from further incursions from Zack Polanski's Greens, Jeremy Corbyn's pseudo-Marxist 'Your Party' and the numerous pro- Palestinian splinter factions.

Second, they believe that by attacking Thatcherism, they are making a break with, not marking a return to, the politics of the past.

As one Starmer ally put it: 'Most voters don't remember the days when the Government ran travel agencies. What matters to them are the private water companies that keeping dumping s**t in their rivers, and the private energy companies that keep ripping them off. And they're well up for taking them on.'

Third and most significantly, Burnham sees a golden opportunity to exploit the widening schism on the political Right.

The Prime Minister's reappropriation of the Left's anti-Thatcher tropes may be intellectually lazy, but in certain areas of the old Red Wall they undoubtedly resonate. And because of the current electoral map, those areas will be key to providing the Prime Minister with a path to a fresh majority and his own mandate.

'Keir won a majority of 170 with less than 34 per cent of the vote,' a minister explained to me. 'So we don't need to construct a Tony Blair style 'big tent'.

'As long as the Tories and Reform remain at each other's throats, we just need to convince enough working- voters to give Andy a proper chance to clear up [Rishi] Sunak and Keir's mess, and we're in business.'

The attraction of this 'core vote strategy' is there for all to see. Reform's 18-month lead in the polls has stalled, even reversed. Kemi Badenoch is slowly but surely overtaking Nigel Farage.

And if, at a future election, Labour and Reform were effectively tied in the share of the popular vote, Andy Burnham would secure 100 more seats than his closest rival.

But there are also major risks with his 'Proper Labour' masterplan: not least that a tax-and-spender is sitting in No 10 when the nation has nothing left to tax or spend.

The consensus among MPs from all parties was that Burnham bested Badenoch in their first PMQs exchange yesterday. But her warning over the fractiousness of the bond markets was not cheap political point-scoring.

As my colleague Alex Brummer writes today (see page 7), the economic dashboard is flashing red. The price of ten-year gilts is now above the level that precipitated the market crisis that saw Liz Truss ejected from office.

Unless the Government gets a grip on public spending in next month's Budget, a similarly catastrophic collision with fiscal reality is inevitable.

As is a collision with the electorate. In response to Badenoch's charge that he had yet to identify anything to cut, Burnham responded he had cut VAT on fuel bills. It was a sharp reply, and worked well in the Chamber.

In Burnham's world, significant tax or spending cuts are simply not an option.

At PMQs he repeated his commitment to ensuring a sharp rise in defence spending. His stated desire to find savings to welfare has already been diluted by his pledge that they be secured 'not through crude cuts but in a way that provides the right support for people'.

He has also made expensive- sounding promises to 'end rough sleeping', alleviate the cost of living crisis and comprehensively reform social care.

So his options are limited. He can increase the burden on business, and further suffocate Britain's anaemic growth.

He can hike taxes on working people, guaranteeing a repeat of Starmer's implosion of public support.

Or he can quietly scale back his pseudo-socialist populism – a move that would invite charges of callowness and betrayal from the parliamentary Labour Party.

For the moment, Andy Burnham deserves credit for at least being true to himself.

He looks at politics through the prism of class. He dislikes Margaret Thatcher and he actively despises the hold he believes the Iron Lady has had over British politics, and the Labour Party, for almost half a century. As Blair himself said after leaving office: 'My job was to build on some Thatcher policies.'

For the moment, that makes Burnham a difficult target for his opponents to attack.

In the end, however, there is no escaping political and economic gravity. The gap between what the Prime Minister aspires to do and the resources available for him to do it is simply too wide.

Kemi Badenoch is right. Andy Burnham is going to need to learn to say 'no'. Before the people of Britain do it for him.