It starred Roger Delgado as Professor Josef Gomez, Maurice Denham as Hugh Deverill MP, David Spenser as Dr. Ken Richards and Miriam Margolyes as Mrs. Wilson.
[1] The Slide was Victor Pemberton's first science fiction story; it was accepted as a radio serial commissioned by future Doctor Who producer Peter Bryant.
Victor Pemberton originally submitted The Slide to the BBC TV series Doctor Who in 1964; it was rejected by script-editor David Whitaker, but following a revision it did inspire the story Fury from the Deep.
The story was to feature the Doctor, Ian, Barbara and Vicki discovering sentient mud invading London from a fishing bay.
In September 2020, the serial was included as a bonus feature on the DVD & Blu-Ray release for the animated reconstruction of Fury from the Deep.