but that could equally have been the intentional running-down of the show from a director who disliked the show.
I seem to remember some interview that it was the director general of the BBC (Grade?) at the time who didn't like the show, so ordered it dropped
"In 1985 the channel's controller Michael Grade attempted to cancel the series, but this became an 18-month hiatus instead. He also had Colin Baker removed from the starring role in 1986. The role was recast with Sylvester McCoy, but falling viewing numbers, a decline in the public perception of the show and a less-prominent transmission slot saw production ended in 1989 by Peter Cregeen, the BBC's new head of series. Although it was effectively cancelled with the decision not to commission a planned 27th season, which would have been broadcast in 1990, the BBC repeatedly affirmed, over several years, that the series would return."
And this about the Seventh Doctor
"Although Michael Grade had left the BBC in 1987 to take up a new position as Chief Executive of Channel 4, Doctor Who remained in its poor slot opposite Coronation Street in seasons of only fourteen 25-minute episodes, and continued to suffer in the ratings. Jonathan Powell, the new Controller of BBC 1, regarded Nathan-Turner with contempt, and the BBC's new Head of Series, Peter Cregeen, decided to cancel the series, a decision which was clear to the production team by the end of production on the twenty-sixth season in August 1989."