Chris Mullin’s 1986 book, Error of Judgement: The Truth About The Birmingham Bombings, helped to expose the miscarriage of justice suffered by the Birmingham Six convicted for the bombings, who were eventually exonerated in 1991.

West Midlands Police (WMP) applied for an order under the Terrorism Act 2000 requiring Mr Mullin to disclose material relating to his investigation of the bombings in 1985 and 1986.

Rejecting the application, the Recorder of London, Judge Mark Lucraft QC, said: “The journalism in issue was of the highest public interest value exposing serious failings on the part of the criminal justice system which resulted in the wrongful conviction and imprisonment of six innocent men.

“In my judgment on all the facts of this case, I agree with the submission of [Mr Mullin’s counsel, Gavin Millar QC] that there is not an overriding public interest in denying the Article 10 rights that are in play.”

Mr Mullin’s solicitor, Louis Charalambous of Simons Muirhead Burton, said: “This is a landmark freedom of expression decision which properly recognises the public interest in Chris Mullin’s journalism which led to the release of the Birmingham Six. If a confidential source cannot rely on a journalist’s promise of lifelong protection, then these investigations will never see the light of day.”