Genesis of the Daleks - S12-E4
Trivia: The actor who played Davros, Michael Wisher, always wore a kilt to the studio, as he preferred it to trousers. It is never seen, of course, as his lower body is always hidden inside his Dalek chair. (Source: DVD commentary).
Other mistake: The Brigadier says UNIT HQ is 'a Top Secret establishment'. It is, in fact, so secret that it has a large sign outside informing the world not only of its function, but also the name of the commanding officer.
The Doctor: This is a situation that requires tact and finesse. Fortunately, I am blessed with both.
Question: In which season and episode is Gallifrey destroyed, or is it just a shocking new plot development for the new series?
Answer: It was never destroyed on-screen; it was intact at the end of the TV movie, and destroyed by the start of the 2005 series. It was destroyed in the novel "The Ancestor Cell," but in a completely different manner to what happened in the series.
DaveJB