Perhaps the most striking example of the tonal shift was the introduction of a Kid-Appeal Character - the robot dog K9 - as a companion to the Doctor. During Williams' three seasons, the show also became steadily more comedic, culminating in Douglas Adams becoming script editor for his final season.
After three seasons, Williams moved on. His successor was the former production unit manager John Nathan-Turner, who would reverse the trend of the Williams era and take the show in a far less comedic direction.
Having left the television industry to run a hotel, Graham Williams died in a shooting accident in 1990, aged just 45.