Australian national Jeffrey Revell-Reade, who was extradited from his home country in 2012, is currently serving nine-and-a-half years for what is believed to be one of the largest boiler room frauds ever pursued by a UK authority.
In addition to the jail term, which was handed down in June 2014, Revell-Reade was ordered to pay £10.75m under a confiscation order in April 2016.
He made a successful appeal in April 2017 to have the order reduced to £7.5m, but has since only paid around £3.5m.
As a result, a further four-year prison sentence was activated by Westminister Magistrates’ Court on Tuesday.
The extra jail time does not alleviate the confiscation order as Revell-Reade remains liable for the full amount once his sentence is served.
His co-conspirator Anthony May was given a term of seven years and six months and ordered to pay £250,000.
The SFO said this has been paid in full.
Revell-Reade and May were found guilty of setting up bogus stockbroking firms in Madrid that used high-pressure sales tactics to flog shares in US-listed companies.
The pair claimed the shares had resale restrictions of 12 months.
When the investors came to sell the shares after the expiry of this period, they often found that they were worthless, and that the shares were in shell companies or companies that were not operating at all.
Between 2003 and 2007, the scheme pocketed £70m from UK investors.
Their convictions were linked to seven other individuals, also convicted and sentenced following a seven-year investigation by the SFO.
In activating the default sentence, district judge Snow said: “I have no doubt at all that given his record of offending, given his failure to meet the order, given the lies he has told previously and given the bogus high court claim, that the assets are available to Mr Revell-Reade as found by the Crown Court and that the reason for his behaviour is that he is wilfully refusing to settle his order.”