The BBC’s head of news, James Harding, has vowed to broadcast a Panorama episode about undercover journalist Mazher Mahmood once new information has been evaluated – saying the corporation does not want to ‘trip up over a detail’.

The programme, featuring up-to-date images of the ‘Fake Sheikh’, was not broadcast last night despite a ruling in the Court of Appeal not to grant Mr Mahmood an injunction to stop the screening.

The BBC made the decision after receiving new information relating to one case in the documentary from Mr Mahmood’s lawyers.

Mr Harding said in a speech to the Society of Editors that the show would be screened as soon as possible.

“This is a seriously good piece of work, extremely revealing and squarely in the public interest,” he said. “But the worst of all worlds is when you get the big picture right and trip up over a detail.

“So when some information we’d been asking to see for many days was sent to us by Mazher Mahmood’s lawyers at seven o’clock last night, we, as a responsible broadcaster, had to consider it. We’re looking at it, and we’ll make sense of it as quickly as we can, and then we’ll broadcast it.”

Mr Mahmood had launched a last-minute challenge against a High Court judge’s refusal on Friday to grant him an injunction.

He claimed that revealing his current appearance would breach his human rights by exacerbating the existing risk to his safety caused by his investigative work and would impact upon his family life.

But yesterday Lord Justice Elias and Lady Justice Sharp refused him permission to appeal, saying he had not shown any error in Sir David Eady’s ruling.

Despite the outcome in court, the BBC decided instead to show a Panorama episode investigating the disappearance of Blackpool schoolgirl Charlene Downes.

A BBC spokesman said last night: “The BBC had intended to broadcast Panorama, Fake Sheikh: Exposed tonight following the Court of Appeal’s decision earlier today to allow the BBC to broadcast images of Mazher Mahmood.

“Shortly before transmission, Mr Mahmood’s lawyers submitted new information relating to one of the cases in the programme which, as a responsible broadcaster, the BBC needs to evaluate.

“Once this has been done we will broadcast Fake Sheikh: Exposed, including recent footage of Mr Mahmood, as planned.”

The programme, described by Mr Mahmood’s counsel, Justin Rushbrooke QC, as a ‘hatchet job’, aims to shed light on the methods used by the reporter who exposed various personalities while working at the now defunct News of the World, using his disguise as a sheikh.

He was criticised after the collapse of the drugs trial of pop star Tulisa Contostavlos in July, when a judge said there were grounds to believe he had lied.

Mr Mahmood, who denies any wrongdoing and has not been charged, is currently suspended by the Sun and a number of cases in which he was set to be a witness have been dropped by the Crown Prosecution Service while investigations continue.

The injunction he sought would have covered any images taken since April 5 2006 not already in the public domain.

His lawyers said he lives a reclusive life in secure accommodation with 24-hour surveillance and where his neighbours do not know his real identity.

But Manuel Barca QC, for the BBC, said his identity is no secret and the case is not about any fears for his safety but about protecting his livelihood and the shelf life of his professional stock-in-trade.

Counsel said the public interest is self-evident, not least in the context of the Contostavlos trial.

The appeal judges agreed with Sir David that Mr Mahmood had not shown that any risk to him would be materially increased by the use of recent images, given that his identity is known and that a “welter” of pictures of him exist – albeit that some were pixillated.