Of the eight actors who took the part over while the show was running, as opposed to doing so in new launches, only two – Pertwee and Smith – have ever had their debut story also serve as a companion debut. Furthermore, only twice has regeneration also marked a wholesale change in the major production staff (producer or script editor for the classic series, executive producer for the new) – Tom Baker and, again, Matt Smith – although the Pertwee and McCoy had a reshuffle.
