Which phrase? I want to give credit where credit is due. Didn't realize I was plagiarizing!
I don't think anyone thinks that, so it's cool and a common phrase probably isn't plagiarizing, like "You're fired".
But to answer your question it's: Keep Calm and Carry On.
Churchhill was addressing the residents of London and they did in fact Keep Calm and Carry On. During the day, they would wear uniforms, and go about their jobs, going into work there may be a sign up in front of a bombed out building, that said, Moved next door.
And then in the evening they would put on suits and silky dresses and go into basements and dance and sing, while air raid sirens went off and drowned out the singer, who just kept on singing.
Part of the rest of that speech was something like:
...and carry on we will. We will carry on until death or victory. (if you can imagine Churchill's voice)