* Journalist gave evidence against UK PM's ex-media chief
* Judge spares him jail for helping prosecution
* Security guards acquitted of Rebekah Brooks cover-up
LONDON, July 24 (Reuters) - A former tabloid reporter who admitted hacking hundreds of phones to find stories for two Sunday newspapers was spared jail on Thursday for helping secure the conviction of Prime Minister David Cameron's ex-media chief Andy Coulson.
Dan Evans gave evidence for the prosecution during the eight-month trial of Coulson, who was jailed for 18 months earlier in July for his role in widespread phone-hacking at Rupert Murdoch's News of the World title.
Shortly before the trial, Evans made a deal with prosecutors and admitted he had carried out more than 1,000 hacks involving some 200 victims - mainly celebrities but also sports stars and politicians - while working for the now defunct Murdoch title and its rival, the Sunday Mirror.
He also admitted lying about hacking in a legal action brought by one of his victims, and illegally paying a prison officer and a policeman for information.
Giving evidence, Evans said his targets included the likes of James Bond actor Daniel Craig, and he said "even the office cat" knew that phone-hacking was rife at the News of the World under Coulson.
The judge, John Saunders, said his crimes warranted 10 months in prison but he suspended the jail term because of the help Evans had given and might give in future trials.
"I would not have done that had Mr Evans not made a clean breast of his involvement in these offences," he told London's Old Bailey court, adding the lack of witnesses prepared to testify about hacking made Evans's position unique.
He said: "It became clear in the trial that I have just completed, that getting people who work in newspapers to give evidence of phone-hacking is extremely difficult, if not impossible."
Two other former senior journalists who admitted carrying out extensive hacking on behalf of the paper have been jailed as well as Coulson, while a private detective and another ex-journalist also pleaded guilty to roles in the activity.
Evans began his hacking activities at the Sunday Mirror, learning from a senior executive, and it became a major part of his job, his lawyer Jonathan Turner said.
He was poached in January 2005 by News of the World managers who were keen to secure his hacking skills and "was engaged on a frightening scale making these calls," Turner told the court.
Hacking ended at the News of the World when police arrested the paper's royal editor in August 2006.
But under pressure to find stories, Evans returned to his old ways in 2009 and was caught out when trying to access the voicemails of interior designer Kelly Hoppen, who was suspected of having an affair with pop star Madonna's ex-husband, film director Guy Ritchie.
He initially lied about what had happened, blaming "sticky keys" on his mobile phone, but eventually told the truth after his arrest.
Coulson edited the News of the World from 2003 until he quit in 2007 when the former royal editor was jailed. Months later he began working for Cameron but resigned in 2011 when the phone-hacking scandal re-emerged as a major issue.
While Coulson was convicted, Rebekah Brooks, who ran News International, the British newspaper arm of Murdoch's News Corp. was cleared of charges relating to hacking, authorising illegal payments, and trying to hinder the police investigation.
Earlier on Thursday, judge Saunders formally delivered not guilty verdicts against four security guards who had been accused of helping Brooks and her husband hide material from detectives.
Coulson faces a re-trial on charges he authorised illegal payments, and other journalists from Murdoch newspapers have been arrested or charged with a variety of offences.
Prosecutors are also still weighing whether corporate charges should be brought against News International. (Editing by Catherine Evans)