The 'Brexit' battle in Britain is heating up as economists go toe-to-toe over what would happen. No country has ever left the EU or its predecessor, the Common Market, since the trade alliance's inception some 60 years ago.

It's here in Britain's high-rolling financial district where worries over Britain leaving the EU are at their height. With earnings making up to 10 percent of the UK economy, it's feared the UK capital's role as a global financial center could be undermined. A report from government economists has warned a Brexit would cost British families up to $6,000 dollars a year.

"If we left the EU, we'd lose tens of billions of pounds in money for our public services, because our economy would be smaller and our families poorer," said George Osborne, UK finance minister.

Other research from the International Monetary Fund, the World Bank and the Organisation for Economic Co-operation and Development arrives at similar conclusions-quitting the EU would hit the UK populace in the pocket.

"The 'Brexit tax' would be a pure deadweight loss-a cost incurred with no economic benefit," said Angel Gurria, OECD secretary general.

Europe's most powerful leader, German Chancellor Angela Merkel, says 'UK don't go' while, U.S. President Barack Obama, says there'll be no special trade deals.

Obama said, "And UK is going to be in the back of the queue."

So the question is: why would British Prime Minister David Cameron risk a referendum if a global consensus is stacked against a UK exit?

In part this polish shop signposts the reason ?An influx of Europeans from across the EU finding work in Britain under the Union's Freedom of Movement rules.

Hammering home that point, the 'Out' campaigners say they want control of their borders.

"Ultimately, what this referendum is really all about is: should we be in control?" said Nigel Farage, UKIP leader.

And so popular became that message, the government proposed an 'in/out' referendum. The latest opinion polls suggesting the result could go either way.