The award-winning 'fake sheikh' who terrifies the rich and famous

Mazher Mahmood is one of the biggest names in tabloid journalism. However, his most famous, or infamous, triumphs have been achieved under elaborate fictitious personae.

Mr Mahmood and his employers, the News of the World boast that they have been responsible for more than 100 people going to jail. In the process, it is claimed, he has had a £100,000 contract taken out on his life and regularly has to change his address to escape retribution of the underworld.

In 1999, he won the prize for reporter of the year at the British Press Awards for his exposé of Newcastle United Football Club directors Freddie Shepherd and Doug Hall. Slurping the champagne supplied by Mr Mahmood, they called Geordie women "dogs" and crowed about how much money could be made from selling replica kits to their gullible football fans.

On that occasion, Mr Mahmood was pretending to be a rich Arab. The "fake sheikh" is his favourite disguise, and appears to have worked with remarkable consistency.

It seems 1999 was a vintage year for Mr Mahmood "the Arab". Radio 2 presenter Johnnie Walker fell for the "sheikh" and was secretly filmed cutting cocaine in a London hotel. He pleaded guilty to possession and was fined £2,000. London's Burning actor John Alford was jailed for nine months for supplying coke and cannabis to the "sheikh". Soon afterwards Lord Hardwicke took cocaine with the "sheikh", and got a suspended sentence of nine months.

Two years later came an even higher-profile victim. The Countess of Wessex made indiscreet and insulting remarks about the Royal Family, Tony Blair and William Hague to a man she saw as a wealthy sheikh, and a potentially highly lucrative client. The fall-out resulted in the Countess having to give up her business life.

But Mr Mahmood's triumphs also attracted criticism that he was acting as an agent provocateur and that continued to remain a crucial factor in court proceedings.

Mr Walker was fined rather than jailed because the magistrate disapproved of the methods of Mr Mahmood and his newspaper, and the jury at the trial of Lord Hardwicke were so appalled by Mr Mahmood's behaviour they asked the judge to spare the accused a prison sentence. He obliged.

A case against footballer Ryan Giggs' brother, Rhodri, was abandoned last year after the prosecution acknowledged it could not rely on taped conversations between him and Mr Mahmood. Mr Giggs was acquitted of supplying cocaine, and the judge asked the CPS to consider bringing charges of incitement to supply drugs, and illegal possession against the reporter.

After the "Beckham Gang" were arrested, the News of the World spoke of how "proud" they were of Mr Mahmood and his sidekick Conrad Brown, the "courageous duo" who are "what fearless popular journalism is all about".

It is unlikely that the latest reverse in the court would change the attitude of the newspaper's hierarchy. Mr Mahmood and his sensational stings sell a lot of newspapers. But it may make the police and the Crown Prosecution Service, think hard about bringing cases based on his "fearless popular journalism".