By Martin Hickman.Andy Coulson's admission that he knew about the hacking of David Blunkett has been "hung around his neck like an albatross" at the phone hacking trial, his lawyer said today.Making his closing speech, Timothy Langdale QC, said that Mr Coulson's account of the News of the World's interception of the Home Secretary's messages stood up to scrutiny.On learning Mr Blunkett had been hacked over his relationship with the publisher Kimberley Quinn, Mr Coulson had immediately told the chief reporter Neville Thurlbeck to halt the hacking.He had only decided to publish the exclusive about Mr Blunkett's "affair" several weeks later in the belief that it was in the public interest, because in his messages to Mrs Quinn, the politician had mentioned a visit to GCHQ and a terrorist arrest.Mr Langdale added that this original justification for the story had regrettably become "blurred" in the front-page that was actually published, because of the NoW's friendship with Mr Blunkett, and the possibility of the MP seeking a privacy injunction.He added that the prosecution was wrong to suggest that Mr Coulson had done nothing to prevent further phone hacking at the News of the World because under his editorship the paper had established its "School of Excellence".When in the following year, 2005, Mr Coulson had tried to contact another hacking victim, Hannah Pawlby - political advisor to another Home Secretary, Charles Clarke - the News of the World's editor had not been seeking to establish whether they were having an affair, Mr Langdale said.Instead, Mr Coulson's calls to her phone - tape recorded and mistakenly deleted by the NoW's specialist phone hacker, Glenn Mulcaire - were probably about Ronnie Biggs, ID cards or an "anti-bullying campaign," Mr Langdale suggested.He said that Mr Coulson had also had played no part in the hacking of another figure linked to Mr Blunkett, his friend, estate agent Sally Anderson.He told the court that Mr Coulson had not known that the paper had hacked the phone of Milly Dowler. "Mr Coulson's evidence is that he did not know her phone had been hacked and that if he did, he would have been very concerned," Mr Langdale said.Mr Coulson had not despatched a team of photographers and reporters to Telford to investigate the theory that the 13-year-old was working at a factory, saying: "The editor cannot micro-manage the reports in the paper."Mr Langdale said his client believed that the £100,000-a-year budget for Mulcaire's company, Nine Consultancy, would save money on other legitimate private detective work.The QC said: "He never inquired in any detail what they actually did. Why should he?"Mr Counson, editor of the News of the World between 2003 and 2007, has pleaded not guilty to one count of conspiring to hack phones and not guilty to two counts of conspiring to commit misconduct in public office.The trial continues.