Doctor Omega

You may be looking for the series in the real world.

Doctor Omega was a television series watched by Jonathan James, featuring Omega in sci-fi adventures with his allies Fred and Captain Borel. (PROSE: The Forgotten Son) The titular character was played by Cyril Cusack in the 1960s, an era in which it caused the "Kelptonmania". (PROSE: Beast of Fang Rock) Sally Wright saw one playing in a department store. (PROSE: Domination Game) Alistair Gordon Lethbridge-Stewart apparently resembled the actor behind Captain Borel.(PROSE: The Forgotten Son)

The series was cancelled and replaced by Fear Frequency. (PROSE: Fear Frequency)

Behind the scenes

The Lethbridge-Stewart series of publications seems to imply that a televised adaptation of Doctor Omega is the in-universe version of the Hartnell era of Doctor Who with its Dalekmania being replaced by one based on the Kelptons and Hartnell by an actor actually considered by David Whitaker at the time. (DWM 207)