Mike Yates

Captain Michael Alexander Raymond Yates (commonly known as Mike Yates) worked alongside Brigadier Lethbridge-Stewart, Benton and the Third Doctor in UNIT.

UNIT career
Yates began as an enlisted man in UNIT. When he first met the Doctor, then in his third body, Yates had just come off of what he called "clean-up duty". During the Doctor's early exile on Earth, Yates had been tasked with combing the British countryside for signs of Auton and Silurian debris. The Brigadier assigned him to headquarters duty around the time of the investigation in the South Pacific that led UNIT into an encounter with the Brokk. He established a good working relationship with Dr Liz Shaw and formed a fast friendship with his fellow sergeant, Benton. He also came to see UNIT as cash-strapped. The Brigadier took Yates into his confidence and admitted neither the UN nor the UK government would give UNIT enough money for additional officers. He was forced to ask that Yates and Benton shoulder more responsibility than would typically be required of non-commissioned officers. (MA: The Eye of the Giant) Some time thereafter UNIT's budgetary woes apparently lessened. Yates was promoted to Captain at the end of an adventure involving Glasshouse and the Silurians. (MA: The Scales of Injustice)

Yates was cool under fire, efficient, and both gave and carried out orders with a minimum of fuss. Despite his somewhat aristocratic demeanour, he had a good rapport with his men, although he did remind Benton on occasion that "rank has its privileges". (DW: Day of the Daleks) He was attracted to the Doctor's assistant Jo Grant. (DW: The Curse of Peladon) He accompanied the two of them to the planet Karfel. (MA: Speed of Flight)

Dismissal
The chain of events leading to Yates' retirement from UNIT started when, while undercover, he was hypnotized by the computer BOSS. The Doctor used the Metebelis crystal to break the mind control. (DW: The Green Death) Yates' brush with ecological disaster apparently made him very concerned about the future of the planet. He was easily recruited by Sir Charles Grover into the secret Operation Golden Age project, which would have reverted the whole of Earth to prehistoric times. The conspiracy was thwarted by the Doctor. In return for his past service to UNIT, the Brigadier allowed Yates to take medical leave and quietly resign. (DW: Invasion of the Dinosaurs)

Aftermath
Mike later decided to go to a Buddhist meditation centre to find solace. Here, he uncovered strange events, which he reported to Sarah Jane Smith, since he felt that UNIT would consider him untrustworthy. Sarah communicated this to the Doctor. Through it all, the Doctor still considered him an ally. (DW: Planet of the Spiders)

He briefly met the Fourth Doctor at the Brigadier's Christmas party. (AG: The Stuff of Nightmares)

In 1976, he helped the Seventh Doctor defeat the Vardans. (NA: No Future)

In 2010, Yates was apparently living with a man named Tom. He discussed Benton in polari with Alexander Shuttleworth, a gay man. (NA: Happy Endings)

At some point after his retirement from UNIT, Yates answered a magazine advertisement seeming directed specifically for him about "light household duties" leading him to a house called Nest Cottage. There he reunited with the Fourth Doctor, who told him about his encounters with the alien Hornets. (AG: The Stuff of Nightmares, The Dead Shoes, et al)

Personality
Though as a young man his life he presented himself as straight and very "laddish", (PDA: The Devil Goblins from Neptune) he later realised his attraction to men. This is not necessarily inconsistent, as they portray different periods of his life. By 1976 he had, however, entered into a relationship with another man. (NA: No Future)

Behind the scenes

 * Richard Franklin wrote a play featuring Franklin both as himself and as Yates (alongside Benton) called Recall UNIT: The Great Tea-Bag Mystery. He also wrote an unpublished novel featuring Mike Yates, The Killing Stone, set after the events of Planet of the Spiders. It was released as an audio book, read by Franklin, by BBV in 2002. It is unknown if the characters used were licenced by the BBC.
 * More recently, a "guest book" entry on the tie-in website "Who is Doctor Who?" created by the BBC for the 2005 series saying how the Doctor changed his life (not necessarily for the better) is signed by a "Mr Yates", a possible reference to the character. In it, he warns off those investigating him, stating "I think it might be in your best interest to not concern yourself with the Doctor or his doings. He is not the man you think he is and he is not involved in the manner you think he is. I should know, he changed my life completely. The Doctor is protected by friends in high places. "
 * While his romantic life was unexplored in the TV series, spin-off media portraying his later life identified him as either gay or bisexual; depending on one's perspective of canon, this could make Yates the show's first LGBT character.
 * Franklin reprised the role of Yates for a series of five BBC Audio dramas under the umbrella title Hornets' Nest which were released during the second half of 2009, alongside Tom Baker. He continued this performance in the two sequel series Demon Quest (2010) and Serpent Crest (2011).
 * Mike Yates appeared once more on TV in DW: Dimensions in Time, a canonically ambiguous story.