Michael Richards, and Jonathan Anwyl, both of East Sussex, Dubai-based Robert Gold, Rodney Whiston-Dew from London and Evdoros Chrysanthos Demetriou from Oxford, were all jailed for more than 43 years in 2017 for the £107.9m fraud, which was one of the UK’s biggest tax crimes.

At the Old Bailey in October and Southwark Crown Court in December, the five have now been ordered to pay a combined total of £20m or serve a further 39 years in prison.

Gold may need to sell a property in Dubai to settle his £2.6m bill, and Anwyl has cashed in his pension fund to meet his £250,000 order. Anwyl has paid his order and Gold has until late January 2020 to pay up or face an extra jail term of nine years.

Richards, who faces repaying £9.9m, and Whiston-Dew, who must find £3m, have properties in West Sussex and South-West London which they may need to sell to pay off their respective orders. Otherwise Richards will face a further 10 years in jail, and Whiston-Dew an additional nine years. Demetriou has the choice of paying over £4.6m or a further nine years in prison.

The sixth member of the crime group, Malcolm Gold, previously of Hertfordshire was sentenced to 20 months in prison in January 2017. He was subject to a confiscation order for £4,711, which was the amount of assets he had available at the time, and this order has been paid.

If further assets are identified in the future for any of the convicted men, they could also be confiscated.

The five men were convicted of tax crimes after HMRC investigators found they lured wealthy individuals to invest in carbon emission reduction certificates, which help countries hit environmental emissions targets set by the United Nations.

They created, marketed and administered a tax incentivised investment scheme which was intended to create a claim for sideways loss relief against income tax. The scheme was supposed to support re-forestation projects abroad, largely in Brazil, which would absorb carbon and so address climate change.

However, in reality the money was diverted to purchase properties in the UK and Dubai, none of which was declared to HMRC.

A ten-month long trial at Southwark Crown Court heard evidence that some 730 high net worth individuals invested large sums of money and claimed tax relief of over £107m in what the judge described as ‘a very effective fraud based on a very bad reforestation project’.

Martin Lynagh, assistant director, fraud investigation service, HMRC, said: ‘This was a carefully-planned and complex attack on the tax system and now the men have to pay up or spend even more time in prison, and still owe the money.

‘Our actions don’t stop once someone is convicted, we will look to reclaim the stolen money, cash that should be funding vital public services in the UK’.