There is no escape from the fact that the News of the World was well known to be involved in making corrupt payments to police officers in the late 1990s and in the early 2000s.

As a former BBC home affairs correspondent, I had written extensively about police corruption. The Guardian carried two long stories by me in 2002 naming the News of the World under the headings "Journalists caught on tape in police bugging" and "Fraudster squad". More detail came the following year in my book Bent Coppers.

I had obtained confidential Scotland Yard reports and other documents relating to a bugging operation conducted against a south London private detective agency called Southern Investigations, suspected of receiving leaks of information from corrupt detectives which was then sold on to tabloid newspapers, among them the News of the World and the Sunday Mirror.

The agency's two principals, Jonathan Rees and ex-detective sergeant Sid Fillery, had both been arrested in connection with the 1987 murder of Rees's former partner, Daniel Morgan, found in a pub car park with an axe embedded in his head. For some years, the agency and its associates had played a part in setting up newspaper stings, providing information and bodyguards to the likes of the News of the World's "fake sheikh", Maz Mahmood.

But of greater concern was its gathering from police and other sources of scandalous information about celebrities and establishment figures, including politicians and members of the royal family, as well as the belief that some police operations were being jeopardised through leaks to the media.

I quoted in the Guardian from an internal police report which warned anti-corruption officers planting the bugs at the agency to be extra careful because their targets were "alert, cunning and devious individuals who have current knowledge of investigative methods and techniques which may be used against them. Such is their level of access to individuals within the police, through professional and social contacts, that the threat of compromise to any conventional investigation against them is constant and very real."

Another report quoted in the Guardian said: "Rees and others have for a number of years been involved in the long-term penetration of police and intelligence sources … They have ensured that they have live sources within the Metropolitan police service and have sought to recruit sources within other police forces. Their thirst for knowledge is driven by profit to be accrued from the media."

A report on just one month of bugging at the agency shows an officer passing on information about the Yorkshire Ripper, Peter Sutcliffe, and high-profile prisoners awaiting trial. Information from police working on the murder of the TV presenter Jill Dando was also being received and re-sold to newspapers. An officer in the royalty protection squad was giving information, including a tip that the marriage of two minor members of the royal family was in trouble.

Transcripts of the bugging operation identify Alex Marunchak of the News of the World as one of the agency's lucrative customers. In a telephone conversation, Rees said Marunchak owed the agency £7,555. The transcript says that the money would be paid in the name Media Investigations, with Rees adding that the account would be "back within the agreed limit" by the following week.

Asked at the time by the Guardian if he disputed buying material from Rees, Marunchak replied: "You haven't heard me admit it."

The anti-corruption investigators hoped that their operation would result in long custodial sentences for both police and journalists. "The Metropolitan police will undoubtedly benefit if a journalist is convicted of corrupting serving police officers," said another confidential report. "This will send a clear message to members of the media to consider their own ethical and illegal involvement with employees of the Met in the future."

But it was not to be. Instead, in 2002, Rees, another man and a detective were all jailed after being found guilty of conspiracy to pervert the course of justice which involved the planting of drugs on an innocent woman. Fillery received a community rehabilitation order after admitting 15 counts of making indecent images of children.

No journalist was charged as a result of the anti-corruption operation, the view apparently being that it could not be proved that the reporters knew that the information they were receiving and paying for came from corrupt officers.

After Rees came out of prison, he resumed working with the media, particularly with Marunchak of the News of the World. But in early 2008, Rees and three other men were charged with the axe murder of Daniel Morgan, and Fillery was charged with conspiracy to pervert the course of justice.

Their Old Bailey trial was expected to hear details of the agency's dealings with the media, and the allegation that Morgan was murdered because he was about to expose police corruption. But after long legal argument the trial collapsed earlier this year without it even getting in front of a jury.

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