A pack of fraudsters led by a Carshalton couple swindled a cancer hospital out of so much money unpaid bills almost caused catastrophic effects for patients.

Stacey Tipler, a former worker at the Royal Marsden NHS Foundation Trust, based in Sutton, and her partner Scott Chaplin led a "sophisticated and ingenious" plan that resulted in more than £642,000 being stolen from the specialist cancer hospital.

The duo, of Tintern Road, recruited a gang of friends and acquaintances to help them launder the money but ended up getting caught out when an error on their part led to bills going unpaid and a company threatening to stop the supply of life-saving drugs to the hospital.

Tipler, 32, and Chaplin, 33, were jailed for four years and five-and-a-half years respectively at Southwark Crown Court this morning while their accomplices - Adrian Horan, 42, of Tull Street in Mitcham, William Flynn, 37, of Birchwood Avenue in Wallington, Clinton Woollery, 35, of Brooklyn Close in Carshalton, Russell Baker, 32, of Idmiston Square in Worcester Park, Thomas Quinlan, 26, of Banstead High Street, and Roy Harriott, 32, of Henley Avenue in Sutton were also sentenced.

The scam was Chaplin's idea and he orchestrated the laundering of the money through bank accounts of his associates but it relied on Tipler's position working in the accounts payable department of the hospital.

She devised a system that would allow her to divert payments from the hospital to the other conspirators until April 2012 when she knew the hospital was switching to a new system whereby invoices would be dealt with via a central NHS department.

However, she failed to put a stop to some of the diverted payments by the time the switch happened meaning it was not long until the companies affected became aware their invoices were not being paid.

Judge Anthony Leonard QC, sentencing, said: "It could only have been you who came up with the sophisticated and ingenious fraud that could go on undetected.

"The fact that you failed to reverse the scam could have had catastrophic effects for patients because one supplier threatened to stop supplying medicines to the hospital until they were paid what they were owed."

The money was laundered through the accounts of the other conspirators who took varying shares of the proceeds and gave the rest to Chaplin. The court was told the gang spent the money on luxury goods including a parachute jump, Apple gadgets and Gucci and Louis Vuitton goods.

Chaplin and Tipler used some of their proceeds to pay their mortgage and put down a £3,000 deposit for their wedding.

Woollery was jailed for 10 months, Harriott was given a 12 week suspended prison term, Horan was given a 21 month prison sentence, Quinlan, 26 was given eight months in jail, Flynn, 35, was sentenced to 12 months in prison and Baker was given a nine week suspended jail term.

Sue Frith, head of the national investigation service at NHS Protect, said: "This gang stole a large amount of money from the NHS which was intended for patient care.

"The Royal Marsden is world-famous for its treatment of cancer patients and the funds stolen could have paid for radiotherapy, chemotherapy and cancer drugs."