Between December 2007 and December 2011, Jessica Harper submitted false invoices to claim payments totalling £2,463,750.88, to which she was not entitled before laundering the money.

She has now pleaded guilty at Southwark Crown Court to one count of fraud by abuse of position and one count of money laundering and will be sentenced on 21 September.

Sue Patten, head, central fraud division, Crown Prosecution Service, says: "Jessica Harper has today been convicted of the type of crime the bank employed her to combat. The evidence in the case was clear and left Harper with little choice but to plead guilty."