Doctor Who - Season 7 (1970)

It was the first series produced and broadcast in colour and the first set entirely in one time period and almost entirely on Earth (the latter of these factors would later be repeated for Season 26 and Series 1, although in those two cases there was no attempt at an in-universe explanation for confining the Doctor to the planet). Although the series did not have an overall story arc, it did feature a recurring subplot of the Doctor trying to adjust to life as an exile while trying to circumvent the restrictions placed upon him by the Time Lords, and began the process where the Doctor would try to gain more control over his TARDIS. Beginning with this series and continuing for the next few years, most storylines involve the Doctor working with UNIT.