Slater

 was a U.N.I.T. soldier in the late 20th century. He was best friends with McCrae. McCrae and Slater were sexist, often discussing the attractiveness of women in their vicinityy, including Romana. They barely survived an attach by a group of daemons from a parellel world. Afterwards, the two seemed more respectful and quiet. (PDA: Heart of TARDIS)