Along with John Fraser as Dixon Druce in the "Madame Sara" episode of 'The Rivals Of Sherlock Holmes' were two major players in the 'Doctor Who' cast of characters.
Caroline Johns played the doomed Edith Dallas. She was probably the Doctor's most capable and efficient Companions during the course of the series, working with the Third Incarnation of the Gallifreyan Time Lord.
As Edith's much older half-brother, Roger Delgado may have had no choice but to exude that air of villainy. He was the first - and best! - incarnation of the Doctor's arch-nemesis, the Master. But by first, I mean he was the first that we met, but he was the last incarnation from the natural regenerations granted to a Time Lord (at that time). There should have been twelve more incarnations before him.
Funny thing was, Delgado's performance never made me think of the Master. However, because he was in a wheelchair, Davros came to mind....