A Robin Hood Tax on the banks could raise tens of billions to help protect public services, fight poverty and tackle climate change at home and abroad.

This tax has gathered support from dozens of countries, including Germany, France, South Africa and Brazil. Bill Gates, Archbishop Rowan Williams, the Vatican and 1,000 economists have added their support. Yet the U.K. Government is continuing to resist this growing international pressure to introduce a Robin Hood Tax.

It’s simple: the financial crisis and the recession have left a massive hole in the U.K.’s public finances. Jobs and public services are at risk in the U.K. while many other developed and developing countries face a similar struggle.

But there is another way. Thousands of Robin Hood supporters believe that banks, hedge funds and the rest of the financial sector should pay their fair share to clear up the mess they helped create.

In a nutshell, the big idea behind the Robin Hood Tax is to generate billions of pounds – hopefully even hundreds of billions of pounds. That money will fight poverty in the U.K. and overseas. It will tackle climate change. And it will come from fairer taxation of the financial sector.

A tiny tax on the financial sector can generate £20 billion annually in the U.K. alone. That's enough to protect schools and hospitals. Enough to stop massive cuts across the public sector. Enough to build new lives around the world – and to deal with the new climate challenges our world is facing.

As a result of the financial crisis, the International Monetary Fund (IMF) has calculated U.K. government debt will be 40% higher. That 40% equates to £737 billion pounds, or £28,000 pounds for every taxpayer in the country. Having to pay back that debt means cuts in vital services on which millions of people around the country rely.

Total cost to the U.K. of financial crisis in terms of lost output according to the IMF was 27% of 2008 GDP.

So it's time for justice. It's time for justice for ordinary families and businesses. For the one in five British families faced with a choice between buying food or paying the heating bill. For the millions of people around the world forced into poverty by a financial crisis they did absolutely nothing to bring about.

The Robin Hood Tax is justice. The banks can afford it. The systems are in place to collect it. It won't affect ordinary members of the public, their bank accounts or their savings. It's fair, it's timely, and it's possible.

It is an idea for which the time has come.