Members of Britain's largest skunk cannabis smuggling ring carried holdalls stuffed with hundreds of thousands of pounds in cash to launder at a foreign exchange, a court heard today.
The gang had so much money they left bundles of bank notes rotting in a forgotten underground safe.
To get around the problem they used an east London bureau de change to clean up their dirty profits, Southwark Crown Court heard.
Members of the gang were seen carrying bags stuffed with up to £200,000 into the World Currency Exchange.
A money counting machine recovered from the bureau de change had processed 520,000 individual notes - the equivalent of £10 million in £20 bills - the court heard.
Ringleader Terrence Bowler and 11 other gang members are facing jail.
The gang brought at least £62 million of skunk cannabis into the UK hidden in boxes of flowers from Holland.
At one point they were shipping in consignments worth up to £750,000 a week.
Timothy Cray, prosecuting, said their activities amounted to "organised crime involving drug smuggling and money laundering on a massive scale".
He told the court police had the gang under surveillance from August 2007 to November 2008.
The defendants used rented lock-ups and garages in south-west London and north Surrey to store the drugs.
Mr Cray said: "The cash-rich nature of the business set the defendants a number of challenges.
"Storage of these amounts of money was something that caused the conspirators difficulty."
He said one garage used by the defendants had built-in floor safes where £392,000 in cash was found, including £60,000 which had rotted through water damage.
He said money was laundered at the World Currency Exchange, run by defendant Asim Bashir, where it was hidden among legitimate transactions.
Mr Cray said: "The holdalls they carried in there contained approximately, as a maximum, £200,000 in £20 notes."
When the men were arrested police seized 2,125lb (964kg) of skunk and £550,000 in cash.
Mr Cray said: "Big as these seizures were, there is clear evidence to suggest that they were just the tip of a large criminal iceberg.
"Only the defendants themselves will ever know the full extent of the drugs they imported into this country and the money that was generated as a result."
Mr Cray described Bowler as the gang's "number one" and a "senior controlling figure in the criminal group".
Bowler associated with all the principal conspirators, holding regular meetings, dealing with problems and meeting new recruits, the court heard.
Mr Cray said he enjoyed a lifestyle "with many of the trappings of worldly success," including a house in Kingston where £75,000 worth of jewellery was found.
The 14-month undercover investigation found that the drugs were imported into the UK through Harwich ferry port in Essex and taken to a warehouse in Chatham, Kent.
Officers at the port intercepted a shipment of 494lb (224kg), worth more than £750,000 to the gang, on July 16 2008, prompting a major change in tactics by the criminals.
From September 2008, the drugs were shipped to Hull and taken to a warehouse in Leeds before being transported to one of a number of lock-up garages in Kingston, Worcester Park, Epsom and Ashtead, where the skunk cannabis would be unpacked and stored.
Bowler, 40, of St Albans Road, Kingston, Surrey; Peter Moran, 37, of Fulham Palace Road, Fulham, west London; and Mark Kinnimont, 40, of Claremont Road, Surbiton, Surrey, made up the gang's "board of directors", and all pleaded guilty to conspiracy to import controlled drugs and conspiracy to launder the proceeds of crime.
Liam Salter, David Couchman and Timothy Sullivan represented the next level of authority.
Salter, 39, of Reeds Rest Lane, Tadworth, Surrey; Couchman, 38, of Sweeney Crescent, Southwark, south London; and Sullivan, 38, of Ash Court, Epsom, Surrey, all pleaded guilty to conspiracy to supply controlled drugs and conspiracy to launder the proceeds of crime.
Bashir, 35, of The Drive, Ilford, Essex, made sure the drug money was included with legitimate cash and laundered through the financial system. He was convicted of laundering the proceeds of crime.
Roger Alexander, 44, of Churchill Close, High Wycombe, Buckinghamshire, sold much of the imported product, earning £150 to £175 per kilo. He admitted conspiracy to supply controlled goods and conspiracy to launder the proceeds of crime.
Peter Brown, 37, of King Henry's Road, Kingston, was a late entrant into the operation, only joining in September 2008, but was key once the drugs started being imported to Leeds via Hull.
He was witnessed meeting dealer Barrie Burn, 59, of Hinton Road, Bristol. Both men pleaded guilty to conspiracy to supply controlled drugs.
Andrew West, 36, of Willowbank Gardens, Tadworth, was a driver for the gang and pleaded guilty to conspiracy to launder the proceeds of crime.
Another driver, James Hay, 31, of Stonny Croft, Ashtead, who helped to transport drugs and money, was found guilty of possession with intent to supply controlled drugs.
The court heard the drugs were shipped in from Holland at an import price of £2,200 per kilogram.
The gang then sold the cannabis on to regional distributors at a UK wholesale price of £3,400 per kilogram, with 20-50kg being sold at a time.
Mr Cray said regional distributors like Alexander charged £3,550 to £3,575 per kilogram.
Mr Cray said although he was further down the hierarchy, Alexander was still a "prolific drug dealer at a regional level in the High Wycombe area".
He said a "typical deal" would be for Alexander to take 40kg of skunk worth £136,000 and sell it on for a profit of £6,000-£7,000.
The hearing was adjourned to tomorrow when the men will be sentenced.