Fake Sheikh Mazher Mahmood jailed for 15 months for tampering with Tulisa evidence

As he was sent down, a man, believed to be one of Mahmood's alleged victims, shouted from the public gallery "your turn now Mazher".

The reputation Mahmood had hoped to boost by getting Miss Contostavlos convicted now lies in tatters as he was immediately sacked by News UK.

The media giant said it was preparing to "vigorously" defend any civil claims brought over Mahmood's past stings.

In the wake of the Tulisa trial collapse, the Crown Prosecution Service dropped a number of live cases which had involved Mahmood and reviewed 25 past convictions.

Six of those involving mainly high-profile individuals have been taken up by the Criminal Cases Review Commission (CCRC).

Following the guilty verdicts last month, it was further announced that 18 civil claims were being launched against Mahmood, which could total some £800 million.

Sentencing, Judge Gerald Gordon told the pair: "You have been convicted by the jury of conspiring to pervert the course of justice. You, Alan Smith, agreed to and did alter your original witness statement to remove the passage that you both realised could be used to support Tulisa Contostavlos's case in an entrapment hearing.

"Mazher Mahmood, it was your idea. You were the intended beneficiary and you made use of a loyal person, partly an employee, in order to achieve your purpose.

"The motive was to preserve and enhance your reputation. You wanted another scalp and Miss Contostavlos's conviction would have achieved that. And to achieve that, when you saw a problem, you were prepared for the court to be deceived."

Judge Gordon acknowledged a letter from the editor of the Sun on Sunday as well as one from the defendant's mother's GP.

He also sentenced Smith to 12 months suspended for two years, saying he had been motivated in part by "misguided loyalty".

In mitigation, John Kelsey-Fry QC, had said Mahmood stood before the court as a "very frightened man".

Of the divorced father-of-one, Mr Kelsey-Fry said: "He has brought catastrophe upon himself and a lifetime's work will be forever tarnished."

Following the sentence, some of Mahmood's alleged sting victims gathered outside the Old Bailey to call on Parliament to "cleanse this stain on our democracy once and for all".

Former London's Burning star John Alford, whose case is among those being taken up by the CCRC, said: "It's taken over 20 years for some of us, but finally a judge and a jury of our peers has woken up to Mazher Mahmood's lies.

"We would now like to ask Parliament to honour their promise to the British people and implement Leveson part two.

"Our three estates, the monarch, our Parliament and our judicial system, must be held accountable, yes?

"But they must not be held to ransom by a corrupt or unscrupulous press. So please let's cleanse this stain on our democracy once and for all."

A News UK spokesman said: "Mazher has led scores of successful investigations during his 25-year career with the company. His work has led to the exposure of criminality and wrongdoing. It is a source of great regret that his time with the company should end in this manner.

"The previous criminal cases that have resulted from his investigations were tested by the courts or guilty pleas were entered.

"We are aware that the Crown Prosecution Service has reviewed some cases and understand that the Criminal Cases Review Commission is looking at whether a small number of matters should be referred back to the Court of Appeal. We await their decisions.

"We have noted the threats made after Mazher's conviction of civil claims against this company in relation to his previous work. Should such claims be brought, they will be vigorously defended."

The Old Bailey trial had heard that Mahmood and Smith conspired to suppress evidence in the N-Dubz star's trial, which was thrown out at Southwark Crown Court in July 2014.

The singer had been accused of arranging for Mahmood to be sold £800 of cocaine by one of her contacts following an elaborate sting for The Sun on Sunday in May 2013.

During a meeting at the Metropolitan Hotel in London, Mahmood posed as a film producer and plied Miss Contostavlos with alcohol as they discussed an acting role alongside Hollywood star Leonardo DiCaprio.

As Smith drove the former X Factor judge home to Hertfordshire, she allegedly spoke about a family member who had a drugs problem.

When he was interviewed by police about the journey more than a year later, Smith, of Dereham, Norfolk, recalled the conversation.

But a day later, after speaking to Mahmood and emailing his draft statement, the singer's anti-drugs comments were removed, the court heard.

At a pre-trial hearing, Mahmood, of Purley, south London, denied being an "agent provocateur" or that he discussed the drugs conversation with Smith.

But when he was questioned at length in the trial, Mahmood appeared to concede he had talked to Smith about what Miss Contostavlos said about drugs in the car. The case was subsequently thrown out.

Neither defendant gave evidence but it was said on Mahmood's behalf that there had been a "misunderstanding" of his evidence as he was "steamrollered" with multi-faceted questions.