Twitter for Simon Jenkins: It's not only the Queen. We're all screaming for an answer

The latest Occam's razor award goes to Her Majesty the Queen. In the unlikely surroundings of the London School of Economics, she last week cut to the quick. Describing the credit crunch as "awful", she tapped a gilded economist on the proverbial shoulder and asked: "Why did nobody notice?"

Aha, ahem, said the director of research, Professor Luis Garicano. He had clearly been briefed to chat about the weather, corgis and perhaps the Grand National. He had certainly not expected an upper cut to the jaw. Monarchs are not supposed to ask leading questions, even when the nation is screaming for an answer.

With his vocation suddenly on trial, the professor stammered, "Someone was relying on somebody else," adding, as if in moral afterthought, "and everyone thought they were doing the right thing." It was the authentic cry of the blame-shedder down the ages. It wasn't us, ma'm, we were only obeying orders and collecting salaries.

The Queen clearly felt that not since Ethelred the Unready had her office been so blatantly let down by those paid to guard its security. Once upon a time the gallows would have beckoned. Now the Queen wanted only to know what the hell had gone wrong. She gets nothing but sycophancy from her privy counsellors, so why not ask those paid to watch the entrails of the sacred geese, the economists? How had they allowed this monumental screw-up?

Economists claim to understand these things. They have grants, research projects and consultancies. They do graphs and extrapolations. They make mathematical models - the nearest their science gets to a goose entrail - believing that therein lies their mastery of the universe.

We owe Garicano a debt at least for revealing something like the truth. Economists regard it as their duty fearlessly to offer government what it wants to hear. The vets did it over foot and mouth. The spies did it over weapons of mass destruction. The planners are doing it over rural development; the diplomats over Afghanistan. Don't rock the boat, says the modern profession, and the indexed pension is secure.

An army of economists and financial advisers have, for the past decade, reassured the British government that the deregulated money market introduced in the late 1980s held the key to national prosperity. This was intended to beat America at its own deregulation game.

This gave intellectual legitimacy to the City's incentive bonus culture, to offshore private finance, non-dom taxation, wildcat lending to public services and, most recklessly, the hurling of money at poor people so they - and the politicians - could pretend they "owned their own home". This, of course, they did not. The banks did.

An entire profession now appears to have suffered a collapse. Last week the Bank of England decided, overnight, that the ideal way to grapple with the financial crisis was not with a high interest rate policy but with a low one.

This week a political community adamantly opposed to cutting taxes, indeed having begged and borrowed from Asia rather than do so, suddenly thought tax cuts an excellent thing. This was not Keynes finding a new opinion when the facts no longer supported the old one. It was a colossal U-turn.

One Bank of England interest rate setter, David Blanchflower, had howled for six months that the Bank was driving the economy into recession by adhering to Gordon Brown's mindless edict on inflation. He was publicly lambasted. Not until the Bank was clearly given the third degree by Westminster did policy go into reverse and a 1.5 point rate cut was ordained. I trust we hear no more nonsense about Bank autonomy.

Has one of Blanchflower's opponents admitted fault, shown contrition or resigned? Not to my knowledge. They must have cost tens of thousands of jobs, but they were doubtless adhering to the economist's Hippocratic oath: blame others and always claim to be right.

I bear no ill will to the governor of the Bank of England, the monetary policy committee, Treasury ministers and officials, the Financial Services Authority and other members of the nation's economic high command. Some of the ills visited on us this autumn were exacerbated from abroad and some were the result of dodgy bankers, presumably below the regulatory radar.

That is hardly an excuse. This autumn has been the economic equivalent of the Dardanelles. Specific policy decisions had been taken on fixing rates, protecting depositors, isolating mortgage lending, rescuing banks, taxing bonuses and regulating financial products. All appear to have been misguided. The decisions have been reversed when the heat was on; they were decisions informed by experts.

Bank chairmen who wrongly structured their loan portfolios resigned. Doctors who kill people are debarred. Captains who lose ships are court martialled. If journalists make mistakes, even if they cost neither money nor jobs, they may be castigated by a tribunal or sued. Editors are sacked for the wrongdoings of their staff.

Most people regard some sense of accountability as essential to professional trust. Everyone in any job would claim, in Garicano's words, to be "doing the right thing". But to a profession, such a claim is not enough. Trust is essential.

Economics boasts its understanding of how society works, based on a corpus of knowledge and experience. Its influence goes to the heart of domestic policy. Just last spring the prime minister and chancellor were advised by their economists that they could proclaim the stability and prosperity of the British economy into the future.

Since then Britain has passed into recession, with extraordinary abruptness, through a series of failures of policy and regulation. This was not an epidemic or a natural disaster. It was like the Falklands invasion, a catastrophe British ministers and their advisers refused to believe would happen.

Thousands will now be thrown out of work, millions made poorer, hopes dashed, opportunities lost, perhaps more than anywhere else in Europe. Someone should be held accountable. Otherwise the same mistakes will be repeated and nobody will believe what an economist says again. In other words, the Queen deserves a proper answer.

simon.jenkins@guardian.co.uk