The call came through to me in the foyer of Aldgate East underground. It was a lawyer from probably the most expensive legal firm in the country, Farrar & Co. They acted for the Queen, but now they were on the case for Rupert Murdoch’s News International and Mazher Mahmood, otherwise known as the Fake Sheikh. The message was that I, and my friend the then MP George Galloway, had been injuncted and prevented from publishing photographs of the News of the World’s ‘Fake Sheikh’ – the man who had just weeks earlier exposed the greed of the England manager (sound familiar?) Sven-Göran Eriksson.

This was March 2006 – and the story I am about to tell exemplifies just how Mahmood set about entrapping his victims and how, with the collusion of his employers and the Metropolitan police, he brought shame and misery to many of his victims, not to mention costing the public purse millions in futile criminal cases, and how he could and should have been stopped right there.

Mahmood was found guilty on Wednesday of conspiring to pervert the course of justice. The 53-year-old was found to have altered evidence in the collapsed drugs trial of singer Tulisa Contostavlos. His driver, Alan Smith, 67, was also found guilty of the same charge following a trial at the Old Bailey. Lawyers say 18 other people targeted by Mahmood now plan to bring civil claims against him, which could total £800m. Some of the individuals were convicted of crimes which, they argued at the time, came as the result of false evidence.

A few weeks before that phone call at Aldgate tube, Galloway had finally agreed to meet a Middle Eastern businessman who claimed to be a great admirer and who wanted to help his campaigns. The persistent invitation had come through the owner of a Muslim television channel who was particularly keen that they should all meet, probably because he sought investment in his company. The venue was the Grosvenor hotel on a Sunday evening.

The businessman, expensively suited and later to be unmasked as Mahmood, was accompanied by another Asian man and it was explained that he was the Mayfair arm of the global business empire. Galloway was suspicious. This supposed devout Muslim was dripping in jewellery – frowned on in Islam – and didn’t appear to know much about the religion.

Mahmood tried first to press riches on Galloway, he wanted to donate to his work. This, it was explained, would be illegal because he was a foreign national, or claimed to be. But, Mahmood pressed, the cash could be filtered through the Mayfair operation? Again, no.

He then moved it on to “the Jews”, making disparaging anti-Semitic references and pressing the MP to agree. Again this was firmly rejected.

“After dessert”, Mahmood says in his book, Confessions of a Fake Sheik, “Galloway enjoyed a coffee and posed for a picture with myself and my minder Jaws”. Jaws was a giant of a man with gold teeth and inset diamonds.

It was at this point that Galloway became almost certain this was a set-up by the then News of the World reporter. He recalled a section about the Fake Sheikh in Andrew Marr’s book My Trade which contained a description of Jaws. And there he was, ostensibly the chauffeur and minder, smiling blindingly in the foyer.

Jaws was Mahmood Quershi, the Sheikh’s cousin and a former petty criminal in Bradford, complicit in many of the stings.

He had been a crucial player in the bogus story about an attempt to kidnap Victoria Beckham. Five men were arrested and put on trial but the case collapsed when a key witness, who had been paid £10,000 by the News of the World, was revealed as a serial fantasist and criminal. At a subsequent libel trial Jaws admitted that he had incited the putative gang members on the urging of Mahmood.

But the stinger was about to be stung. Aided by a member of the royal family. Princess Michael of Kent, aka Princess Pushy, had been fooled by Mahmood when he flew in by helicopter, in flowing robes and headgear, posing as an Arab prince and as a potential buyer for her 17th Century Cotswolds pile, Nether Lypiatt, a snip at £6 million. The princess was characteristically indiscreet, calling Princess Diana bitter and nasty, among other insults, which duly appeared all over the NoW in September 2005.

Mahmood is paranoid about his identity being revealed, he has been allowed to conceal it in court and in front of the Leveson inquiry – claiming that his life would be endangered if he was recognised, whereas the real motive was clearly to protect his livelihood.

However, he had been photographed in front of the helicopter on Princess Michael of Kent’s Cotswolds estate and this photograph would soon be handed over to me, and we intended to publish it after his failed sting.

An injunction, which covered Galloway and I, was issued to prevent publication – the claim being that Mahmood’s safety was at risk

Less than 48 hours later, we had the injunction thrown out. Judge Mitting was not impressed with the safety argument. He concluded: “I am satisfied that the true purpose of this application is not protection of Mr Mahmood’s life and physical integrity but the protection of his earning capacity and position as an investigative journalist and his utility to his employers in that respect.”

We published the picture which was the only image of him seen for more than two decades and is still being run by the BBC.

Galloway demanded transcripts of the Grosvenor meeting from the NoW. The paper refused and Galloway complained of the attempted entrapment of an MP to the Speaker of the House of Commons, the Metropolitan police commissioner and the Crown Prosecution Service. And that should have been that, the Fake Sheikh should have been forced to hang up his dishdasha and his keffiyah but he continued, with the knowledge and collusion of his employers, the police and the CPS.

There were at least two other warnings to the Met about his methods yet they continued to treat his stories as evidence for the basis for criminal cases which led to people being jailed. Indeed according to Scotland Yard sources weekend leave for crucial officers was cancelled when a sting was due to be published.

Last night Galloway told the Sunday Herald: “I have a long history with the Fake Sheikh. I raised his criminal ways in a debate in the House when the actor John Alford was set up and then jailed. [Alford was convicted in 1999 of supplying drugs to Mahmood]. I am now calling on the parliamentary Home Office Select Committee to investigate this unholy conspiracy between him, the police and justice authorities and find out why this was allowed to run and run.”