03/11/2011 19:28 GMT | Updated 03/01/2012 05:12 GMT

Robin Hood Tax Can Still be Agreed at the G20

Packing my bags to depart the G20 in Cannes, I leave with a sense both of what might have been but also inspiring memories and a real hope that the battle for a 'Robin Hood tax' on financial transactions might still be won.

Let's take first what might have been. As expected, Bill Gates presented an excellent report calling for a 'Robin Hood tax' on financial transactions to raise much-needed money for poor countries struggling to cope with the economic crisis and climate change. But the fact his report was published at the same time as the Greek president addressed the world about his country's problems was sadly symbolic of a summit whose attention was trained on Athens at the expense of Accra and Addis Ababa.

With a day still to go this might still change - President Sarkozy's decision to raise the issue of the financial transaction tax during his press conference with President Obama, shows he has not yet given up hope. Germany, Brazil and Argentina also spoke out strongly in favour raising the prospect of a coalition of willing countries that goes beyond Europe's borders. And the

events of recent days, with Mr Gates' call being supported by G20 members from France to Argentina and by senior figures from the Archbishop of Canterbury to Jeff Sachs, shows that momentum is building behind an idea whose time has come.

One of the advantages of being a well-known figure is that it grants me the opportunity to speak in the media on behalf of others. So I spent much of the day bouncing back and forth between the day-glo green windowless bunker where most of the print journalists are housed, and the fifth floor roof terrace where rather windswept interviews took place with a view of Cannes' rather lovely seafront.

But while the media appearances are necessary and valuable, it is the determination of

extraordinary members of the public from around the world that convinces me that this is a fight that can be won. As leaders meet, in Cannes, thousands of nurses are marching in New York to try to convince President Obama to put the interests of Maine Street ahead of the titans of Wall Street. I was lucky enough to meet some representatives of nurses from the US countries around the world who like me, had come to Cannes to continue the campaign.

These are the people who look after the sick who see firsthand the impact the economic crisis both in the richest nation in the world and some of the poorest. As one nurse said: "We're trying to embarrass our politicians into acting in interests of people, like we do every day."

In poor countries, the austerity caused by the financial crisis is literally a matter of life and

death for millions of people who are hungry or who rely on aid to provide their medicines or keep the nearest clinic open. I was impressed by Tim Noonan of the International Trade Union Congress who went straight to the heart of the argument. "Government's should have a contract with their people, not with the banks," he said. When you strip away the technical arguments about derivatives, high frequency trading and credit default swaps, it really is simple: a tiny tax on some of the richest people in the world that could raise billions to help the poorest.

The Greek tragedy may have stalled progress towards a 'Robin Hood Tax'. But my feeling is that the Sheriff of Nottingham's days are numbered.

Oxfam works with others to overcome poverty and suffering.