Doctor Omega

Doctor Omega was a television series watched by John James. (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)

Behind the scenes
The Lethbridge-Stewart series of publications seems to imply that a televised adaption 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)