STORY SPOILER
"As far as I can tell, the story so far is that Bill Paterson's character is some kind of Professor, a boffin working for Churchill during WW2. He believes he's invented the Daleks as a new super-weapon, though he's a bit fuzzy on how the idea came to him. The Daleks are stringing the Prof along, playing docile and very British.
DALEK: "Would you care for some tea?"
Churchill doesn't care where the Professor's "ironclads" came from, only that they have the potential to defeat the Nazis and win the war.
CHURCHILL: "Death to our enemies... Death to the 3rd Reich!"
THE DOCTOR: "Yes, yes, and death to everyone else too."
The Doctor is trying to convince the Prof and Churchill not to unleash the Daleks, but they're not taking him seriously (possibly because he seems implausibly young?) hence his growing frustration and anger, as he turns on the playing-it-innocent Daleks:
THE DOCTOR: "I sent you back into the void. I saved the whole of reality from you. I am the Doctor, and you are the DALEKS!"