1986 (production)


 * 8 April - Filming on The Mysterious Planet began at Queen Elizabeth Country Park in Horndean.
 * End of May - Around the time of Robert Holmes's death, Eric Saward resigned as script editor due to a disagreement with John Nathan-Turner over Saward and Holmes's plans for the final part of the Trial story arc; Nathan-Turner commissioned Pip and Jane Baker to write the final chapter.
 * 14 August - Production concluded on the fourteen-part The Trial of a Time Lord, with a recording session at TV Centre Studio 3 for Terror of the Vervoids. Unknown to most at the time, this would conclude Colin Baker's time as the Doctor on TV.
 * October - According to The Television Companion by Howe and Walker, at some point this month, Colin Baker was informed that his contract to play the Doctor was not being renewed.
 * 6 October - Around this time, BBC Controller Michael Grade approached the originator of Doctor Who, Sydney Newman, for ideas on how to revitalise Doctor Who. In a letter dated 6 October, Newman provided some ideas and suggested he be brought on board as executive producer of the series. He also attempted to be credited as the show's creator. Subsequent meetings, however, failed to result in Newman's return to direct involvement in the series.
 * December - The BBC announced that Colin Baker would not be returning as the Doctor in the next series.