What methods should journalists be allowed to use in order to get a story? The question has been raised again by the jailing of Mazher Mahmood, the undercover reporter nicknamed ‘the Fake Sheikh’, for tampering with evidence in a case involving singer Tulisa Contostavlos. Mahmood’s stories proved embarrassing to a number of high-profile celebrities, including former England manager Sven Goran Eriksson, the Duchess of York and the directors of Newcastle United FC, and a queue of lawsuits is pending.

But Mahmood also produced some important stories. For example, he exposed both footballer John Fashanu and a group of Pakistani cricketers for taking bribes. Nor is Mahmood alone in using such methods. Another former England manager, Sam Allardyce, was forced to resign last month after another undercover sting, where he was secretly filmed explaining how football transfer rules could be circumvented.

Yet the press has already been roundly criticised after the ‘phone hacking’ scandal, in which the answerphone messages of celebrities were trawled through in search of stories, with a number of journalists being jailed for their involvement. While Mahmood may have done important work, the judge at his trial said that he had engaged in criminal activity to ‘preserve and enhance’ his reputation.

What will be the impact of Mahmood’s case on investigative undercover reporting? When journalists pose as other people, is this automatically entrapment? Or is the ability to get important public figures to speak unguardedly vital in uncovering important stories of public interest?