1977 (production)

Unknown Dates

 * Terrance Dicks wrote the script for what would become State of Decay, then known as The Wasting, and later referred to by the titles The Witch Lords and The Vampire Mutations. It wasn't produced until 1980 as the BBC were at the time planning a major drama about Dracula, and feared that a Doctor Who story running concurrently about vampires would either steal their thunder, be considered a send-up of their adaptation of Bram Stoker's story, or both.

January

 * 8-13 January - OB filming for The Talons of Weng-Chiang took place. (REF: Doctor Who The Handbook: The Fourth Doctor)
 * 24-25 January - Studio filming for The Talons of Weng-Chiang took place. (REF: Doctor Who The Handbook: The Fourth Doctor)

February

 * 8-10 February - Studio filming for The Talons of Weng-Chiang took place. (REF: Doctor Who The Handbook: The Fourth Doctor)

April

 * April - Bray filming for The Invisible Enemy took place. (REF: Doctor Who The Handbook: The Fourth Doctor)
 * 10-12 and 24-26 April - Studio filming for The Invisible Enemy took place at BBC Television Centre studio 6. (REF: Doctor Who The Handbook: The Fourth Doctor)