By Ian Dunt
A sting operation by the Daily Telegraph has been criticised by the press watchdog after it used secret recording devices on the business secretary.
Last December's story saw Vince Cable admit to two men he thought were constituents that he considered himself "at war" with Rupert Murdoch and that he would consider resigning if it secured political goals.
Liberal Democrat president Tim Farron complained about the story, saying it threatened MPs' honesty when meeting constituents.
The Press Complaints Commission (PCC) upheld the complaint, saying the level of public interest was not enough to" justify proportionately this level of subterfuge [the use of hidden recording equipment]".
The PCC's editors' code of conduct requires strong public interest for the use of subterfuge.
It explicitly forbids "fishing expeditions" where reporters use subterfuge without any reasons to suspect a story exists but with the off-chance hope of getting one.
The newspaper, "although acting no doubt with legitimate intent", did not have "sufficient grounds, on a prima facie basis, to justify their decision to send the reporters in", the PCC concluded.
Daily Telegraph editor Tony Gallagher accepted the ruling but said it had "alarming implications" for investigative journalism.
He said the dichotomy between Cabinet ministers' public pronouncements and private thoughts following the formation of the coalition was sufficient to justify the methods employed for the story.
"Our revelations led to the demotion of a member of the Cabinet, apologies from a string of junior ministers and condemnation from their party leader," he added.