1980 (production)

Unknown Dates

 * Early 1980 - The BBC announced that K9 would be leaving Doctor Who during the next season. According to The Television Companion by David J. Howe and Stephen James Walker, the response to this announcement by fans inspired John Nathan-Turner to pitch the idea of a spin-off series featuring the character, which later became K9 and Company.

April

 * 30 April - Location filming for State of Decay took place. (REF: Doctor Who The Handbook: The Fourth Doctor)

May

 * 1-2 May - Location filming for State of Decay took place. (REF: Doctor Who The Handbook: The Fourth Doctor)
 * 15-16 May - Studio filming for State of Decay took place at BBC Television Centre studio 3. (REF: Doctor Who The Handbook: The Fourth Doctor)
 * 29-31 May - Studio filming for State of Decay took place at BBC Television Centre studio 6. (REF: Doctor Who The Handbook: The Fourth Doctor)

July

 * 23-25 July - Location filming for Full Circle took place. (REF: Doctor Who The Handbook: The Fourth Doctor)

August

 * 7-8 and 21-23 August -Studio filming for Full Circle took place. (REF: Doctor Who The Handbook: The Fourth Doctor)

September

 * September - John Nathan-Turner approached Peter Davison about taking over from Tom Baker as the star of Doctor Who.

October

 * 24 October - At a press conference, the BBC announced that Tom Baker would too be leaving Doctor Who at the end of the current season.

November

 * November - The BBC announced that Peter Davison had been cast as the Fifth Doctor.