Hacking trial: Andy Coulson tells jury he regrets publishing details of David Blunkett's affair with Kimberley Quinn

Mr Coulson admitted last week that former NOTW journalist Neville Thurlbeck had played him voicemail interceptions that confirmed the relationship

Self-preservation, a desire to “save his own skin”, and the impact a wider police investigation may have had on the News of the World, influenced Andy Coulson's decision in 2006 not to reveal to Scotland Yard that he knew the home secretary's phone had been hacked, a jury at Old Bailey has been told.

The former editor of the now-closed News International tabloid told the hacking trial that although he had not hindered any police investigation, he took the decision not to volunteer that a senior reporter at the NOTW had played him a hacked phone message which detailed the affair David Blunkett was having with the publisher, Kimberley Quinn.

Mr Coulson, 46, denied that he eventually learned the 2006 police investigation into hacking would be “pretty superficial” and would not be widened to include others beyond the former royal editor, Clive Goodman, and the paper's private investigator, Glenn Mulcaire.

Both Goodman and Mulcaire were jailed in 2007, the jury have been told, with NI continuing to explain hacking as the work of a “single rogue reporter” until the end of 2011.

Mr Coulson, who later headed David Cameron's Downing Street communications team, admitted last week that Neville Thurlbeck had played him voicemail interceptions in 2004 that confirmed the Blunkett-Quinn affair.

David Spens QC, defence counsel for Goodman, said the reason Mr Coulson had not told the police about Thurlbeck was a concern to “save his own skin”. Mr Coulson told the jury “I accept the impact on me was a factor.”

The jury have been told that Thurlbeck and two former NOTW newsdesk journalists, pleaded guilty to hacking-related charges earlier in the trial's proceedings

In a sequence of questions from Mr Spens that related to journalists at the NOTW who have admitted direct involvement in phone hacking, Mr Coulson was asked: “All these people worked for you at the NOTW, and you just didn't know?” Mr Coulson replied “No.”

The Blunkett affair story appeared in the NOTW after Mr Coulson had personally interviewed the then home secretary in his Sheffield constituency home. No details of information coming from hacking was given to Mr Blunkett.

Mr Coulson told the jury that he now regretted his decision to publish details of the affair in the NOTW.

He told the court: “This [story] was about someone having an affair, and given what was going on in my personal life, the irony is not lost on me.”

Throughout the trial, which has now last over 100 days, there has been reference to the on-off affair between Mr Coulson and Rebekah Brooks, the former News International chief executive.

Seven defendants in the trial, including Mr Coulson and Mrs Brooks, are charged variously with conspiracy to hack phones, the bribing of public officials and perverting the course of justice. All deny the charges against them.