Abandoning the prosecution against Gun fuelled speculation that the case was dropped to spare the publication of the legal advice.
Gun “could only get a fair trial if we disclosed material to the defence that would compromise national security,” he said.
Sir Ken Macdonald told the Observer he had realised that it would be impossible to give the whistleblower a fair trial without also risking national security.
The film also strays into controversy by alleging that Macdonald paid a private visit to Ben Emmerson QC, who represented Gun, following the whistleblower’s arrest.