Jean Marsh, who had portrayed Joanna in The Crusade (1965) and Sara Kingdom in The Daleks' Master Plan (1965–66), appeared in Battlefield playing the part of the main antagonist.

Season 26 continued Andrew Cartmel's trend of bringing a darker and more mysterious tone to the show, with a particular focus on Ace's past and the Doctor's manipulative nature.

All releases are for DVD unless otherwise indicated: Midway through 1989, Doctor Who's production team began initial planning for Season 27, which would have aired at the end of 1990.

Andrew Cartmel and the writers he had worked with regularly, including Ben Aaronovitch, Ian Briggs, and Marc Platt, brainstormed possible story ideas.

The cancellation of the series meant that no detailed work was undertaken beyond these initial ideas:[19] Four of these five proposed serials were subsequently adapted by the authors alongside Big Finish Productions into audio adventures that were released as part of their Doctor Who: The Lost Stories range in 2011: The only one of the proposed stories that did not receive a release from Big Finish was Alixion.