Data released by the Bank of England stated that 719,000 counterfeit banknotes were discovered and removed from circulation in 2012.
In total, there are nearly 3 billion banknotes in circulation in the United Kingdom.
(How criminals in Peru make counterfeit money with Microsoft Office.)
Source: Penny Anderson and Jill Papworth, “How to spot a fake banknote,” Guardian, October 18, 2013.