An investigation into the purchase of a £959 million development, dubbed Project Blue, has been deemed unlawful after the attempt to eliminate all of the stamp duty in the purchase.

Christian Candy-backed CPC Group, which funds bridging lender Omni Capital, purchased the site in Chelsea in a joint venture alongside billionaire investment firm, Qatari Diar.

A Clifford Chance investigation however, found that the transaction, dubbed Project Blue, had attempted to eliminate all of the stamp duty on the purchase of Chelsea Barracks in London.

The tribunal ruled that Qatari Dier had failed "to put forward evidence of all the factors that may have been taken into account" and failed to establish that tax avoidance was not a factor in its decision to proceed.

Subsequently, Qatari Diar has found itself facing a sizeable tax penalty, with the court ruling Project Blue must cough up £50 million in tax payments to Her Majesty’s Revenue and Customs, £12 million more than what would originally have been paid.

Speaking on the Court’s decision, David Gauke, a Treasury minister, said in the statement: “Entering into a tax-avoidance scheme can cost more than paying the original tax bill, avoidance is complex, expensive and self-defeating.”

Responding to the judgment, Qatari Diar, once Government owned, said: “We will be reviewing the tribunal’s decision in detail with our advisers and considering our next steps.”

“Project Blue has always tried to fully comply with all U.K. taxation matters evidenced by a pre-payment made on account to HMRC of the full amount of the tax originally claimed prior to the hearing. Project Blue will continue to meet all of its tax obligations.”

The decision affects 24 similar commercial real estate transactions and 900 “mass market” residential property deals, amounting £135 million of taxes.

The Consortium had argued its transactions were carried out for commercial purposes and not the tax avoidance scheme that many were accusing, according to a statement from the HMRC.

Qatar Diar, the world’s largest producer of liquefied natural gas, has various other stakes in high-profile U.K. real estate, including the Shard and Harrods .

The joint venture, which took place back in January 2008, was later criticised by Prince Charles, who claimed the development was unsuitable for the area.

Qatari Diar withdrew its planning application and CPC sued, with Qatari Diar later buying out CPC’s share of the project later in 2008.