The fraudster was serving a two year sentence at Lindholme prison near Doncaster, South Yorkshire, when he was allowed to take part in a course to improve his publishing skills.
Police believe the persistent offender, Charles Kanyimo, a 40-year-old Zimbabwean national, used tricks learned in the prison classroom to improve his cheque counterfeiting operation after being released in 2010.
He has since served another jail term for counterfeiting.
The extraordinary oversight by the Prison Service came to light in a ITV documentary broadcast last week, Fraud Squad, which follows the activities of specialist detectives in London.
Det Sgt Phil Elms, of the City of London Police, told the programme: “So in effect they’re in prison but actually improving the quality of the items they’re going to forge.
“They’ll go in there and want to learn a trade, so they’ll go in there and they’ll say ‘Can I learn printing? Can I learn design?’”
Elms, from the force’s Dedicated Card and Payment Crime Unit, said of Kanyimo: “He was arrested by this department previously.
“He’s got previous for two lots of fraud in 2009 where he got imprisonment for two years, consecutive with another fraud where he got another 12 months.”
On a search of Kanyimo’s home detectives discovered 2,000 cheque books hidden inside a cooker.
The cheque frauds carried out by organised crime gangs are operated as a kind of “franchise” by immigrants who meet in detention centres, police suggested.
Det Sgt Gary Ferris, of West Yorkshire Police, told the programme: “They usually get involved in it … as they come into the country seeking asylum.
“They go to one of the asylum centres and then they get introduced to fellow gang members.
“It’s kind of like a franchise. They sell out the franchise of the fraud, so it goes from West Yorkshire to London, to Milton Keynes to Scotland so it spreads out in that kind of way.”
He added: “These people were showing no discernible signs of wealth but we already knew that they were sending back lots of money, cash to Zimbabwe.
“I think personally it’s probably tens of millions of pounds that they’ve hid away in our investigation and are probably still having away now.”