Andy’s got his dream job. A lifetime ambition fulfilled. He’s in the Med, sipping beer and making plans. He knows it’ll be tough running a country that’s even bigger than Manchester, but reckons he’s up to it. The public like him. Instagram likes him. And he has big plans. Solve social care. Expand the public sector. Re-industrialise Britain. Smash Nigel Farage and sweep the next election. But there’s a problem.

A £3trillion problem. That’s now the size of Britain’s national debt, which passed that grim milestone this week. The Taxpayers’ Alliance puts the number at £12trillion, once unfunded public sector pensions, PFI contracts and nuclear clean-up costs are included. Whatever the figure, it’s too big for the human brain to grasp. Burnham can’t seem to get his head round it at all.

He should be looking to bring it under control. But every time he opens his mouth, he says something that will make it even bigger. By announcing still more spending. New chancellor John Healey is now looking at fiddling the fiscal rules to borrow an extra £9billion a year. Every penny of which will go on the national debt. But there’s a second, hidden problem. Former Labour chancellor Gordon Brown placed a financial timebomb under Britain. It’s been ticking for almost 30 years. Now it could blow up on Burnham’s watch.

Straight after Tony Blair won the 1997 election. Brown launched a stealth raid on the nation’s pensions, by scrapping tax relief on dividends. In doing so, he destroyed Britain’s private sector final salary schemes. Today, most private sector workers have to gamble their retirement pot on the stock market. Only public sector workers get guaranteed, inflation-proof incomes.

Millions will be far poorer as a result, but the damage doesn’t end there. Pension schemes and insurers were major investors in UK equities and government bonds. When Brown made his move, they held 75% of UK gilts. Today, it’s below 20%. Overseas investors now hold a third of all gilts. These include foreign hedge funds, institutions and offshore funds.

Britain is now reliant on foreign money to finance its government debt. As former Bank of England governor Mark Carney famously put it, we rely on the “kindness of strangers”. I’d say we’re at their mercy. Many have a much more short-term investment strategy than pension companies. If they’re not happy, they’ll just dump our debt and move on. In a crisis, things can get quickly out of hand. Just ask Liz Truss.

This is a key reason why UK borrrowing costs are the highest in the developed world at almost 5%, the level that spooks markets. The bond market knows we’re in schtuck. Every £1 in £10 the government spends goes on servicing the interest. And it will only rise and rise. Especially with the economy set to grow by just 1% a year, while the population ages.

Burnham and Healey are in total denial. They’d rather buy themselves easy popularity, and keep backbench Labour MPs sweet, than face the truth

This disaster is long in the making. Brown set the debt timebomb, and years of so-called Tory “austerity” failed to defuse it. Andy Burnham certainly isn’t going to tackle it. He either can’t hear it ticking, or hopes to pass it onto the next PM before it explodes. As one day it surely will.