The Man In A Looking Glass

Directors: Cyril Frankel (director)

Writers: Terry Nation, Dennis Spooner

Cast: Steve Forrest as John Mannering, Sue Lloyd as Cordelia Winfield, Bernard Lee as Morgan Travis, Vvonne Furneaux as Selina Travis

Released 1965

From TVGuide.com: "An art dealer poses as a gangster to prevent the theft of Britain's crown jewels."
According to jensencv8.webbly.com, this was "a combination of Masquerade and The Killing", a two-episode (#6 & #7) adventure.