There were summits about how much misery would be imposed on the Greeks – and no trade unions got a say

What you're about to read does, I admit, sound like a conspiracy theory. It involves powerful people meeting in private offices, hundreds of billions of euros, and clandestine deals determining the fates of entire countries. All that's missing is a grassy knoll or a wandering band of illuminati. There are, however, two crucial differences: these events are still unfolding – and they're more worrying than any who-killed-JFK fantasy I've ever heard.

Cast your mind back to the euro crisis talks last year, when the future of Greece was being decided. How much Athens should pay its bailiffs in the banks, on what terms, and the hardship that ordinary Greeks would have to endure as a result.

There were times when the whole of 2011 seemed to be one long European summit, when you heard more about Papandreou and Merkozy than was strictly necessary. Yet you probably didn't catch many references to Charles Dallara and Josef Ackermann.

They're two of the most senior bankers in the world – among the top 1% of the 1%. Dallara served in the Treasury under Ronald Reagan, before moving on to Wall Street, while Ackermann is chief executive of Deutsche Bank. But their role in the euro negotiations, and so in deciding Greece's future, was as representatives of the International Institute for Finance.

The IIF is a lobby group for 450 of the biggest banks in the world, with members including Barclays, RBS and Lloyds. Dallara and Ackermann and their colleagues were present throughout those euro summits, and enjoyed rare and astounding access to European heads of state and other policy-makers. EU and IMF officials consulted the bankers on how much Greece should pay, Europe's commissioner for economic affairs Olli Rehn shared conference calls with them.

You can piece all this together by poring over media reports of the euro summits, although be warned: you'll need a very high tolerance threshold for European TV, and financial newswires. But Dallara and co are also quite happy to toot their own trumpets. After a deal was struck last July, the IIF put out a note bragging about its "catalytic" role and claiming its offer "forms an integral part of a comprehensive package".

By now you'll have guessed the punchline: that July agreement was terrible for the Greeks, and brilliant for the bankers. It was widely panned at the time, for slicing only 21% off the value of Greece's loans, when Angela Merkel and many others agreed that financiers ought to be taking a much bigger hit. As the German government's economic adviser, Wolfgang Franz, later remarked in an interview: "If you look at the 21% and our demand for a 50% participation of private creditors, the financial sector has been very successful." Another way of putting it would be to say that the bankers overpowered even the strongest state in Europe.

None of this was inevitable. Iceland had made it clear that simply defaulting on one's loans didn't immediately lead to economic apocalypse. Across Greece, there were massive, repeated protests about the enormous spending cuts that citizens would suffer by paying off Goldman Sachs and the rest. And there was a growing movement in Greece and Portugal and France, among other countries, questioning the legitimacy of some of these loans.

None of these voters, none of these opinions got even a fraction of the consideration, let alone the face time, that was extended to Dallara and Ackermann. At Corporate Europe Observatory in Brussels, Yiorgos Vassalos has been tracking the negotiations over Greece: by his reckoning only the IIF got to have such personal, close-up access. These were summits settling how much misery would be imposed on the Greek people – and no trade unions or civil society groups got a say in them. "The only key players in those meetings were European governments and the bankers," says Vassalos.

Mindful of appearances, the EU has been less eager to admit to the influence of the bankers' lobby. When European officials were first asked by Corporate Europe Observatory about the extent of IIF access, they responded that it was limited to the Greek government. Only when it was pointed out that the Wall Street Journal and Bloomberg were reporting that Dallara met Merkel and Nicolas Sarkozy at midnight at an October summit to finalise a bigger reduction of the value of Greek debt did the officials back down: the IIF, they agreed, had been negotiating with a range of governments, on a whole host of issues to do with Greece's future.

So the bankers whose excesses helped land Europe in this mess then get to sit round the big EU table, like any other government, and decide who should pay for it. And the answer, unsurprisingly, is: not them. The bigger question is: why finance has been granted such power? In a forthcoming paper entitled Deep Stall, the Centre for Research on Socio-Cultural Change gives one compelling reason: because so many countries across Europe are, through both their public and private sectors, so dependent on financiers in other countries for credit. That includes Britain, which relies on 10 eurozone countries for loans worth over 70% of its annual national income – a higher proportion even than Italy. The tale of the IIF and how it got such a powerful say on the fate of ordinary Greeks is really a chapter in a much bigger story of how governments across the western world got swallowed up by their finance industries.