introduced to new friend Corporal Benton, another member of UNIT and would later become a great ally to him. 3rd Doctor A matter of months later, the Third Doctor arrived on Earth in 'Spearhead in Space' to begin his exile after the Time Lords forced him to regenerate as punishment for his constant inference in time. Throughout the next year or so, the Third Doctor worked for UNIT, alongside old friend Brigadier Lethbridge-Stewart, as their Scientific Advisor in a bid to help them combat alien threats. The Doctor was also introduced to new companion Liz Shaw, who became his assistant until her off-screen departure after 'Inferno' where she returned to Oxford University. Benton also returned to aid the Doctor in 'The Ambassadors of Death' and was now promoted to Sergeant. In 'Terror of the Autons' the Doctor was introduced to new assistant Jo Grant while the audience was introduced to Captain Mike Yates who had been working for UNIT off-screen in the previous season. The UNIT family had begun and would remain for the next three seasons of Doctor Who. Throughout 1975-1976 they would battle against the Autons and the Nestene Consciousness ('Spearhead in Space' and 'Terror of the Autons'), the Silurians ('Doctor Who and the Silurians'), the Axons ('The Claws of Axos'), Azal and Bok ('The Daemons'), the Daleks and Ogrons ('Day of the Daleks'), Omega ('The Three Doctors'), Giant Maggots and BOSS ('The Green Death') and Dinosaurs ('Invasion of the Dinosaurs'). The Master was also a massive reoccurring