Mike Yates

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

UNIT career
Yates began as a sergeant in UNIT together with Benton and 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 his orders with a minimum of fuss. Despite his somewhat aristocratic demeanor, he had a good rapport with his men, although he did remind Benton on occasion that "rank hath 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 Yate's 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 Yates very concerned about the future of the planet, and he was easily recruited by Sir Charles Grover into Grover's secret Operation Golden Age project, which would have reverted the whole of Earth to prehistoric times. The conspiracy was thwarted by the Doctor, and in return for his past service to UNIT, the Brigadier allowed Yates to take medical leave and then quietly resign. (DW: Invasion of the Dinosaurs)

Aftermath


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

Though at an earlier stage of his life he presented himself as straight, and very "laddish", (PDA: The Devil Goblins from Neptune) in later life he came to realise 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. He again worked with the Doctor to defeat the Vardans. (NA: No Future)


 * It is unclear if Yates would identify himself as gay or bisexual.

When, in 1983, the Brigadier reminisced about what had happened to some of the Doctor's UNIT colleagues, he did not reveal what became of Yates. (DW: Mawdryn Undead)

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 shared a series of adventures with the Doctor in his fourth incarnation (BBC Audio: Hornets' Nest).

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.
 * 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.
 * While his romantic life as 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. It should be noted, however, that non-televised works fall into a "grey area" with regards to canonicity.
 * Franklin reprised the role of Yates for a series of five BBC Audio dramas under the umbrella title Hornets' Nest which was released during the second half of 2009, alongside Tom Baker.