Blue John Mines

The Blue John Mine is a show cave in Castleton, Derbyshire, where a variety of fluorite has been mined for several centuries and where out-of-season miners still grant guided tours for visitors. Although one such tour is featured in Episode 475 in 1965 for the street residents, the actual location filming took place outside the nearby Speedwell cavern which has no link to the mining of fluorite. In addition, scenes set inside a (small part) of the cavern were accomplished in the Granada studios in Manchester and no filming took place in the actual cavern itself. The episode is notable for the first appearance in the programme of actor Roy Barraclough who would return seven years later in the role of Alec Gilroy.