All four parts of The Ribos Operation ran over the allocated time, so a significant amount of material was cut for the broadcast version. Some of this material was retained in Ian Marter's novelisation. There was much debate as to whether K9 should return after the problems the prop had caused in season fifteen. The character was popular with younger audiences so, with the assurance that the new prop was more efficient, Graham Williams approved the introduction of K9 Mark II.