When interviewing a public figure, anything said "off the record" should be dealt with the utmost care by the journalist. Whatever follows can inform future articles, give another better context or corrrect false impressions. What is clear at the time is there is a contract of understanding between the politician and the writer.
Not so at the Daily Telegraph who sent undercover reporters to entrap various Lib-Dem ministers to complain about their end of the Coalition deal. Vince Cable disclosed most and rather rashly, to what he thought were young mums from his constituency. Even so he asked them not to repeat his words "outside."
Revealing his zeal to declare a "war on Murdoch" necessitated removing media regulation from his portfolio and would in any other case have deservedly earned a thorough sacking.
However it was not the Telegraph who broke the story but Robert Peston of the Beeb who had been gifted the scoop by someone at the paper who thought the corporate media group was determining editorial decisions. It is easy to see how that impression was made. It looks more like the Torygraph did not lead with this explosive quote about BSkyB takeover because it did not suit their wider interests for Vince to hand the decision to a more lassez faire Tory like Jeremy Hunt.
Perhaps the paper will learn its lesson about undercover reporting. It is totally proportionate when exposing criminal behaviour or corruption. But if it amounts to bugging in person to embarrass then it is shabby, disreputable and threatens future frank disclosure which until now made the worlds of politics and journalism go round.
Also when you deceive you can't manage what information comes out and it may not, like this case, be in your own interests.
Anyhow, without lifting a finger, Murdoch, as ever, is the winner.