http://www.bbc.co.uk/news/business-11148626
A three-year report into currency dealing shows rapid growth in trading, with the majority of business happening in London.
Trade has jumped by 20% in the three years since the last survey was conducted by the Bank for International Settlements (BIS), which is sometimes called the "central bankers' bank".
But London outpaced the average, with turnover up by 25% over the period.
Some $4 trillion (£2.6tn) changes hands around the world every day.
