Tom (Happy Endings)

On the way to Bernice Summerfield's wedding, Mike Yates told Brigadier Lethbridge-Stewart that Tom sent his regards. Yates also had honey in his baggage that he and Tom had produced, intended as a gift for the Brigadier. (PROSE: Happy Endings)

Behind the scenes

 * The suggestion is that Tom and Yates are living together as a gay couple, although this is not explicit. Other possible interpretations are that this individual is the in-universe Tom Baker, whom later stories would indeed indicate was living in the same village as Yates at this point in the timeline, or that Tom is Tom Osgood, Yates' fellow UNIT member.