You could almost sense the relief last week as the attention of the media turned from trying to make sense of the banking crisis to a good old-fashioned political scandal. So much easier to understand, with a promising pantomime cast - a millionaire hedge fund manager, a Russian oligarch, Peter Mandelson (of course) and George Osborne, the Tory party's Buttons, now apparently undone. No more talk of liquidity, of deleveraging, of recapitalisation. The credit crunch is over, isn't it?

Well, not quite. Bankers still haven't a clue what disasters lurk in the tangle of complex derivatives contracts they and their hedge fund borrowers all piled into, so what hope is there for the rest of us? At times like this, I take comfort in the words of Donald Rumsfeld, the former US Defence Secretary: “There are known knowns - things we know we know. There are known unknowns... things we don't know. But there are also unknown unknowns - things we don't know we don't know.” He was talking about Iraq, of course, but there are a lot of similarities, as in both cases the Great American Rescue Plan was written on about three sides of A4, cost $700 billion and quickly fell apart.

There's certainly a great deal I don't know about banking. But as we've all seen recently, there's a lot the bankers don't know about it either. Their ignorance has been all over our screens this year. Mine gets an airing this weekend.

The inspiration to make a series of comic documentaries - comdoms, if you like - about money came from a piece that John Bird and John Fortune performed on The South Bank Show last year. Written at the start of the crisis, their satire on sub-prime lending received more than two million hits on YouTube - a phenomenon by any standards, let alone for an eight-minute exposition on banking. It's certainly clearer than any conversation you'll have with a banker. If my own experience is anything to go by, you lose the thread after about a sentence and a half, and the will to live soon after.

Yet as the year went on, what started out as an attempt to understand the credit crunch became the biggest story of the year. “Isn't it exciting!” said a make-up artist on one show I did this month. Well, yes, kind of. But it's also truly shocking. The curtain has been thrown back on the world of banking and we've seen the Emperor in all his bare glory. As Warren Buffett, doyen of investors, put it, when the tide goes out, you find out who's been swimming naked.

Gazing out over a sea of butt-naked bankers, no wonder the Bank of England's Mervyn King has decided it's time for “the long walk back to boredom”. Bankers don't like exposure that much. But how did we get into a situation when derivatives, an instrument that few people understand (even bankers), were worth $283 trillion, seven times more than the entire world produces in a year?

It's the numbers that are staggering - so much so as to be incomprehensible. When Barings went bust in 1995 (the year after its chairman Peter Baring told a director of the Bank of England that “it's not actually terribly difficult to make money in the securities business”) its loss was £862 million. Today that seems almost laughably small.

When announcing its $700 billion bailout plan this month, a US Treasury spokeswoman admitted the amount of money involved was “not based on any particular datapoint. We just wanted a really big number.”

At the time of its collapse last year, Bear Stearns was borrowing $33 for every dollar it had. It was able to do that under a regulatory system that let banks opt in or out of supervision voluntarily - the banking equivalent of putting a ravenous fox in charge of a Bernard Matthews farm.

On both sides of the Atlantic, fingers are being pointed at the incumbent government, when it was their predecessors who started the rot: over here with the great Tory deregulation of the City in the 1980s, and in America with Bill Clinton's repeal of the Glass-Steagall Act 1933, separating investment banks (the gamblers) from deposit banks (ordinary savers) and his push to extend home loans to lower-income households, taken up with gusto by the mortgage finance company Fannie Mae. (Not the only time Fannie caused Mr Clinton problems.)

But it wasn't just greedy bankers and compliant governments. The madness affected us all to a degree. People took out loans in their pet's name. Others signed up to 120 per cent mortgages. One woman even took out a loan to have her husband murdered. We wanted to get more for our money, however unlikely the source. Why else would people sign up to Icelandic internet accounts with names that sounded like a new brand of razor? “Kaupthing Edge”; “Iceshave”. Why would you do that? Surely it's just one step up from replying to one of those e-mails from Nigeria offering you hundreds of thousands of pounds in return for your banking details. I suppose the excuse, as it has been for bankers and the public down the ages, is that everyone else was doing it. In which case, what precisely distinguished Stan O'Neal (the former boss of Merrill Lynch, severance package $160 million) from Joe Sixpack (average American, income $35,000)?

Yet this is just the visible tip of the iceberg towards which we seem to be steaming. I find it extraordinary that the US economy is kept afloat by the savings of Chinese peasants, or that a £100 share in a Scottish hospital PFI scheme could net you £89 million over 30 years. But I'm not a banker. I just wanted to try to find out how the thing works. Come to think of it, I'm not sure it does.

One thing is for sure. Your relationship with your bank manager has changed. That's inevitable, given that the next time you discuss a loan it's just as likely that he will be borrowing money from you as the other way round. But then he always was. The difference is, we know that now. It's one of the known knowns.

Bremner, Bird and Fortune: Silly Money starts on Sunday at 7pm on Channel 4

Times Recommends

• We have kit and leadership. Let’s go
• Behind the scenes at the biggest deal
• Conferences — what a waste of money