This episode is currently missing from the BBC's television archives after staff wiped the tapes so they could reuse them. This is one of three episodes that are still missing from the archives. The other two are A Stripe for Frazer (1969) and Under Fire (1969).
This episode was planned for transmission on January 20, 1969 at 7:30pm.
This lost episode was remade from the original scripts and premiered on 25th August 2019 The Loneliness of the Long Distance Walker (2019)
This episode is the only one of the entire series to have a scene set in London: the scene in the War Office in Whitehall, which is in London.