Sohail Qureshi, 53, of Newton Mearns, was jailed for seven-and-a-half years after being found guilty of being the brains behind a gang of fraudsters who raided NatWest's accounts by exploiting a flaw in the online banking system.
The gang cashed a string of worthless cheques disguised as payments for Nokia mobile phones, then transferred the money straight to an account in Latvia.
The bank was in the midst of a takeover by RBS in 2004, and staff only noticed more than £15m had been taken when they returned to work after a Bank Holiday.
Qureshi fled to Dubai when the plot was foiled, leaving his associates behind in the UK to be jailed for a total of 54 years in 2008.
He believed he was safe because there was no extradition treaty with the United Arab Emirates at the time he fled.
Howver, after a decade living in the wealthy Arab nation, Qureshi was finally brought back to the UK. He denied any involvement in the fraud during a trial, despite a mountain of evidence against him.
Qureshi admitted knowing the other men involved, but claimed flurries of late-night calls between them were no more than a "chinwag".
He was convicted of conspiracy to defraud, conspiracy to money launder and conspiracy to use false instruments for fraud.
Jailing him at Southwark Crown Court Judge Nicholas Loraine-Smith said: "I have had the opportunity to see you give evidence and I have no doubt that you were a professional and consummate fraudsman.
"I cannot see you merely listening to what others told you - you would have told others to do your bidding and then kept your distance so you could blame them."
Although Qureshi was called the principal architect of the fraud, his associates have been convicted of multiple offences relating to the NatWest scam.
A prominent connection to the city of Glasgow exists, jurors were told.
Qureshi, along with Ian Clark and Syed Alam, "were all involved in the running of a Glasgow-based company called Marryvale Ltd", Mr Aaronberg said. "From 21 October 2002, a serviced office was rented at the Woodside Business Centre, Glasgow."
Marryvale claimed to deal electronic goods and traded with another alleged front company, Britanniacity UK Ltd - a Liverpool-based company run by the Darren Lee and Martin Williams.
Of Qureshi's associates, ringleader Lee Quincey, from Ashton-under-Lyne, Manchester, admitted conspiracy to steal from NatWest and was jailed for five years and 11 months in 2008.
Darren Lee, from Aintree, Liverpool, Martin Williams, from Bootle, Merseyside were each jailed for five years and nine months after they were convicted of conspiracy to steal.
Ian Clark, from Paisley, Renfrewshire - described in court as an "errand boy" - was handed a three-year sentence after he was convicted by a jury of the same offence in 2008.