The Return of the Evil Creator is a story by Laurence Neave, and is a prequel to Time of Zygon (taking place exactly 6 years beforehand). It sees the return of Davros, but the Golder Doctor and Penny manage to thwart his evil plans.
The Museum Keeper and Maid both reappear later in Time of Zygon, where they are out holidaying in the bitterly cold Norfolk weather. Scholars have been left confused as to the personal timelines of Richard and Margret Whoman (who inexplicably are given names in Time of Zygon, rather than the titles based on their vocations). Some have suggested that following the events in this story, they withdrew from working at the Museum due to PTSD. Additionally, the Doctor and Penny may have returned during the lapse of time, hence why their bond seems so strong in Time of Zygon.