How much did the financial crisis of eight years ago cost the world, cost all of us? There are several ways to tackle that question.

One could examine the public bill for bailing out the giant banks that fell over like ninepins. One could look at the mountains of public debt piled up in the wake of the crisis (as governments, thank goodness, carried on spending while tax revenues collapsed in order to stop their economies slumping into new depressions).

One could contemplate the hellish spike in unemployment across the western world during the slump itself – all those people thrown out of jobs as business confidence evaporated, all those wasted resources, those lives damaged.

Back in 2010 Andy Haldane, now the Bank of England’s chief economist, took a “foregone” global GDP approach. He analysed the output we might have enjoyed if the western world’s financial system had not locked up and the world had carried on growing at its previous rate. Haldane came up with the mind-bending figure of between $60 and $200 trillion: between one and five times the entire planet’s GDP.

However it’s calculated, the cost of the global financial crisis was colossal. And we still bear its scars. We are all significantly poorer today because of the stupidity, greed, irresponsibility and, often, downright criminality of a small band of financiers, mostly based in Wall Street and the City of London, whose behaviour combined to push the global financial system to the brink of total collapse. And we should be scared out of our wits over the possibility of a repeat.

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But Donald Trump doesn’t seem perturbed. Instead, the incoming President of the United States gives every impression that he will soon be hustling America – and possibly the entire world – in the direction of another catastrophic financial crisis.

Dodd-Frank was the banking and financial reform legislation passed by Congress in the wake of the 2008 fiasco. As a reform it was grossly inadequate. The gravest failure was that it did not split up the giant too-big-to-fail banks of Wall Street – the likes of JP Morgan, Morgan Stanley, Bank of America and Goldman Sachs – something that was necessary to abolish their neon-illuminated conflicts of interest and to prevent them from being able to shake down the US government again if their market funding dried up.

Yet Dodd-Frank was better than nothing. Far better than nothing. It did prevent investment banks making massive and dangerous bets with their own money. And it did tighten up on consumer protection, putting a stop to some of the more obvious opportunities for bankers to enrich themselves by misselling financial products to the unwitting American public.

But Trump doesn’t like Dodd-Frank. During his campaign he promised to “dismantle” the legislation, without ever giving a coherent reason why.

Trump posed as the champion of “the forgotten men and women of America” on the campaign stump and did not take much money from Wall Street, certainly relative to previous Republican candidates. He paraded himself as the worst nightmare of the corrupt big money lobby.

But it was a con. Since vanquishing Hillary Clinton in November’s election Trump has, in fact, been the financial lobby’s wet dream. He has packed his administration and senior advisory team with former Wall Street financiers, many of them from Goldman Sachs.

And they have not disguised their agenda. Trump’s Wall Street picks have talked about deregulating derivative trading, allowing investment banks to make big bets with their own money again, allowing investments in hedge funds, reducing capital and liquidity requirements and dismantling the ability of regulators to supervise the sprawling shadow banking system. It is as if 2008 never happened.

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“If the Trump administration does just half of what it says it’s going to do in economic policy and financial regulation, another financial crash is almost certain and sooner rather than later,” is the informed verdict of Dennis Kelleher, the head of the Better Markets think tank.

The share price of American bank stocks took off like fizzing fireworks after Trump’s shock November victory. Traders expect Trump to deliver an aggressive deregulation. Expect the lobbying for a parallel deregulation in London and Europe to become irresistible shortly after.

This time it threatens to be worse. Our defences are much weaker than eight years ago. During the last crash central banks cut interest rates from around 5 per cent to zero and bought up trillions of dollars of bonds and loans to stabilise the system. Governments spent vast amounts of public money to stop banks going bust and devastating the wider economy.

But today interest rates across the developed world are still close to zero and government debt is much higher than it was in 2008, giving policymakers considerably less room for manoeuvre if the system fails again.