Tens of millions of pounds of British taxpayers’ money was used to fund terrorists including the 7/7 London bombing network and Osama bin Laden through a UK-based scam that spanned two decades.

A two-year investigation by The Sunday Times revealed that a network of British Asians stole billions of pounds of public money through VAT and benefit fraud, topping up their gains with mortgage and credit card fraud.

One per cent on the group’s gains, a full £80m, was allegedly funnelled into al-Qaeda in Pakistan and Afghanistan, with funds reaching the Pakistani compound stormed by US special forces in the 2011 operation to kill Bin Laden.

The scale of the scam is breathtaking: the group netted around £8bn in public funds alone – almost triple the annual government expenditure on MI5, MI6 and GCHQ.

A web of secrecy still binds this investigation, which was led by HM Revenue & Customs (HMRC) and Special Branch, and prevents the story from being told in full.

At least two years before the 7/7 attacks, HMRC identified ties between the gang defrauding the British public and Shehzad Tanweer, one of the terrorists involved. At the time, senior HMRC officials declined to use their intelligence to mount prosecutions and neutralise the gang.