Two counterfeiters used fake businessmen to swap or exchange fake Scottish £50 and £100 notes for English ones around the capital.
Ringleader Dean Evans, 36, hired people to dress in suits and pretend to shopkeepers around London and the home counties they had returned from a business trip from Scotland.
Falling for the yarn, the shop workers were either then tricked into changing the dodgy notes for real ones or bought small items and pocketed the change.
The dodgy notes were used more than 200 times throughout London and the home counties between March 2016 and October 2017.
The plot aimed to recycle £640,000 of counterfeit Bank of Scotland notes throughout the south of England.
Evans was jailed four years and three months at Croydon Crown Court on Monday after pleading guilty of conspiracy to pass a counterfeit currency note.
His accomplice Samuel Alexander, 25, was sentenced to two years and eight months’ after admitting the same charge.
Evans organised the team of fake businessmen and often followed them in a second vehicle to avoid detection.
He would then get the change from the ‘businessmen’ but sometimes Alexander would step in.
They were arrested by Met’s Organised Crime Command, who were assisted by the National Counterfeit Currency Unit (UKNCO) at the National Crime Agency, which helped to provide intelligence about the method used by the defendants.
Detective Inspector Andy Durham said: “These defendants attempted to use hundreds of thousands of fake Scottish banknotes.
“The arrest of the individuals behind the conspiracy has disrupted the supply of these bank notes and, recent intelligence, suggests very few are left in circulation.
“This case demonstrates how criminals can often create a convincing back story to explain the use of large amounts of cash.
“Incidents of counterfeit notes being used are low but retailers are urged to check banknotes carefully, people trying to use a counterfeit note will often use it to buy a low value item.”