In the 1980s, the BBC became embroiled in a scandal of epic proportions that would result in Special Branch police conducting a raid on the broadcaster's Glasgow headquarters.
It centred around the planned airing in 1986 of Secret Society, a six-part series produced by journalist Duncan Campbell for BBC Scotland. The investigative show included at least two episodes spilling classified details about a top secret spy satellite programme, Project Zircon.
Campbell and his production staff had discovered that funding of the £500 million spy satellite had been withheld from parliament, and that Margaret Thatcher's government had conducted 'secret cabinet committees'.
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A press conference was held on August 20, 1986, informing the public of BBC 2's autumn schedule, including a series that "disclosed information on Government emergency plans in case there is another war".
These were incendiary revelations, and, with a general election fast-approaching, the government were in panic mode. The Project Zircon episode was lifted from the autumn schedule to allow for an investigation to take place.
Under pressure from the government, the BBC's then Director-General Alasdair Milne subsequently decided that the show should not be aired, sparking a media frenzy. In January 1987, the Observer broke the story, running with the headline: "BBC gag on £500m defence secret".
But the fiasco would not end there. That same month, things were about to take a decidedly more sinister turn.
Carrying search warrants under the Official Secrets Act, Special Branch and officers from Strathclyde Police mounted a 28-hour raid on the BBC's Glasgow headquarters at Queen Margaret Drive.
They questioned the broadcaster's National Controller for Scotland, Pat Chalmers, and seized 211 items, mostly cans of film and reams of documents, relating to the Secret Society episodes. Assistant Director-General, Alan Protheroe, was arrested and interrogated.
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Duncan Campbell and his team of researchers were also targeted. Their homes were searched along with the offices of the New Statesman, where Campbell worked on a freelance basis.
Those at the centre of the investigation would be released and the seized tapes returned, but the attempted cover-up would not be quickly forgotten.
The Secret Society findings on "Zircon" would eventually air two years later, but the remaining episode on secret cabinet committees was banned from being broadcast.
Determined to beat the censors, Campbell, using original research material and scripts, teamed up with Channel 4 to make a new version of the episode deemed too hot to handle by the BBC. Channel 4 aired the show in 1991, however, the original version which Campbell produced for the BBC has never been broadcast.
Secret Society has since been made available to watch online on Duncan Campbell's website.
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