1981 (production)

January

 * 8-9 January - Studio filming for Logopolis took place at BBC Television Centre studio 3. (REF: Doctor Who The Handbook: The Fourth Doctor)
 * 22-24 January - Studio filming for Logopolis took place at BBC Television Centre studio 6. (REF: Doctor Who The Handbook: The Fourth Doctor)

April

 * April - John Nathan-Turner wrote a story outline for the proposed K9 and Company spin-off pilot story.
 * 8 April - Castrovalva is commissioned as a script, with a delivery date of 1 June.
 * 13-15 and 28-30 April - Studio filming for Four to Doomsday took place at BBC Television Centre studio 6. (REF: Doctor Who The Handbook: The Fifth Doctor)

May

 * May - John Nathan-Turner and Anthony Root composed a "format document" for a planned spin-off series to be entitled K9 and Company.
 * 12 May - Elisabeth Sladen was officially invited to reprise the role of Sarah Jane Smith for the planned K9 and Company spin-off.

September

 * 1-4 September - Location filming for Castrovalva took place. (REF: Doctor Who The Handbook: The Fifth Doctor)
 * 15-16 September - Studio filming for Castrovalva took place at BBC Television Centre 3. (REF: Doctor Who The Handbook: The Fifth Doctor)
 * 29-30 September - Studio filming for Castrovalva took place at BBC Television Centre 6. (REF: Doctor Who The Handbook: The Fifth Doctor)

October

 * 1 October - Studio filming for Castrovalva took place at BBC Television Centre 6. (REF: Doctor Who The Handbook: The Fifth Doctor)
 * 29 October - Location filming for Earthshock took place. (REF: Doctor Who The Handbook: The Fifth Doctor)

November

 * November - Production of the pilot episode of the planned K9 and Company spin-off series, A Girl's Best Friend, took place.
 * 10-12 and 24-26 November - Studio filming for Earthshock took place. (REF: Doctor Who The Handbook: The Fifth Doctor)