Slater

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