Singled out by the International Monetary Fund last year as being the fastest-growing economy in the G-7, the U.K. still faces criticism that its high current account deficit could push it toward a currency crisis.
Carl Weinberg, chief economist at High Frequency Economics, told CNBC this week that sterling risked a "very big move of very dramatic proportions" as a result of this deficit.
"I think we are at risk of seeing the world just have too many pounds out there to absorb. And sterling is not the world's reserve currency, people don't want to hold it without limit," he said, adding that a crucial moment for the U.K. currency could come "very soon."
The U.K.'s current account deficit was 6.0 percent of gross domestic product (GDP) in the third quarter of 2014, according to the country's Office for National Statistics (ONS). This was a rise from 5.5 percent in the previous quarter and the ONS highlighted a fall in receipts for foreign direct investment, and a rise in payments to foreign direct investors, as an explanation. The limit set by European Union – from which the U.K. has exempted itself – is a deficit of 3 percent of GDP and the current account deficit in the U.S. stood at 2.3 percent of GDP for the last two quarters.
"The balance of payments right now is appalling," Weinberg said. "Every time it's been above 4.5 percent we've had a sterling crash," he added.
Sterling is down 11 percent against the U.S. dollar since June last year, after gaining 15 percent against the greenback between July 2013 and July 2014.