The killings made national headlines in 1993 when two MOT inspectors, Alan Singleton and Simon Bruno, were shot dead at a garage in Stockport, in Greater Manchester.

The evidence produced in court against Bourke seemed compelling. Two mechanics at the garage said they had seen him carry out the shooting which the prosecution claimed was motivated by a dispute about his licence to carry out MOT tests.

As the jury began their deliberations, a gun was found inside Strangeways prison where Bourke was on remand. Amid subsequent heightened security around the court, he was found guilty and given a minimum 25 year sentence. But protesting his innocence all these years means that he may never be eligible for parole so could remain in prison for the rest of his life.

His sister Jo has been tirelessly fighting his case. A chiropodist with no connections to criminals, she began visiting notorious drug dealers and suspected killers to try to gather new evidence that would help clear his name.

Through the work of Jo and other campaigners, Bourke's case is now back with the Criminal Cases Review Commission which they hope will lead to an appeal.

So has Thomas Bourke been the victim of a shocking miscarriage of justice? Simon Cox investigates.

Producer: Sally Chesworth.