Three men have been jailed for a plot to supply more than £12m worth of counterfeit banknotes.
Police found one of the men at a printing unit surrounded by fake £20 notes totalling £5.25m.
A further £5m was found by a dog walker, while £200,000 was scattered on a railway line. £1.6m was taken out of circulation by the Bank of England.
Kent Police said it was "believed to be the biggest conspiracy of this kind in the history of UK policing".
When officers raided a warehouse in Kent House Lane, Beckenham, south London in May 2019, they found Phillip Brown printing money, alongside piles of counterfeit cash, police said.
Brown, 54, of Ash Road, Longfield in Kent, was jailed on Wednesday at Woolwich Crown Court for six years and six months after pleading guilty to conspiring to supply the counterfeit currency.
John Evans, 27, was also given a 10-year sentence after pleading guilty to conspiring to supply the counterfeit currency and another count of attempting to pervert the court of justice.
Police said Evans, of King Georges Walk in Esher, Surrey, was "one of the main players" in the organised criminal group.
Warehouse owner Nicholas Winter, 58, of Elmers End Road, Beckenham, was jailed for six years at the same court on 21 December for conspiring to supply counterfeit currency.
Det Ch Supt Morgan Cronin, of the Kent and Essex Serious Crime Directorate, said: "This was a sophisticated operation but one that was ultimately doomed to failure due to the offenders' mistaken belief that they could carry on undetected."
He added: "Counterfeiting directly funds organised crime and hurts the UK economy by creating losses for businesses, which ultimately affects the cost of the things we buy."