Shada was meant to be the final story of Season 17. However, a combination of rampant inflation in Britain and union strikes prevented its completion. Those parts of the story that were filmed were retained, and John Nathan-Turner was able to reuse them later in two notable ways. In 1983, a few clips of the show were integrated into ‘The Five Doctors’ when Tom Baker proved unavailable for filming. Later, in 1992, the existing footage was integrated with some new linking narration by Baker.
The industrial action occurred due to conflict over which union had jurisdiction over the operation of an elaborate clock that was featured on the BBC children’s programme Play School.
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