Season nine saw no changes taking place amongst either the production team or the regular cast of Doctor Who - the first time this had happened since season one. It was also very similar to the previous season in terms of style and content (although it did have an extra episode overall, which allowed for it to be subdivided into two four-part stories and three six-part stories - a pattern that would be repeated for the remainder of Jon Pertwee's time as the Doctor).
The most significant change was that the Master was featured in only two of the stories, rather than in all of them as had been the case the year before. This left the way clear for the Doctor to be faced with a wider variety of adversaries - including a number making return appearances from earlier periods of the series' history. The first story, indeed, would see him coming up against the most popular monster creations of all.
Season nine had been another successful one for Doctor Who, its ratings and audience appreciation figures both showing a marked overall improvement for the third year in succession. Producer Barry Letts and script editor Terrance Dicks had both contemplated moving on to other projects at the end of the ninth production block - which continued beyond The Time Monster to include one of the following season's stories, Carnival of Monsters - but, delighted with what they had achieved on the series, their BBC superiors persuaded them to stay on and take it into its tenth year of production.