Caul Pornell

Caul Pornell was a historian who studied the Daleks. He popularised the theory that Davros converted the Daleks frozen on Spiridon into the first ranks of his Imperial Daleks. Other historians were unsure about what happened to these Daleks in the aftermath of the Spiridon campaign. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)

Behind the scenes
Caul Pornell is a of Paul Cornell. His theory is a reference to the plot of Emperor of the Daleks!, which Cornell wrote. This account of what happened to the frozen Dalek army on Spiridon was later contradicted by Return of the Daleks, hence why Dalek: The Astounding Untold History presents the issue in-universe as an unresolved historical conundrum.