I have a few favorites :)

Lionel: Do you know the "f" word?
King George VI: Ffff... fornication?

Lionel: You still stammered on the 'W'.
King George VI: Well I had to throw in a few so they knew it was me.

Queen Elizabeth: My husband's work involves a great deal of public speaking.
Lionel: Then he should change jobs.
Queen Elizabeth: He can't.
Lionel: What is he, an indentured servant?
Queen Elizabeth: Something like that.

Lol, here's one I really liked. I don't remember it exactly, but here's the gist:

Lionel: No smoking in my house.
George: My court physicians say it relaxes the throat!
Lionel: Then they're a bunch of idiots.
George: They've all been knighted!
Lionel: Makes it official then.

My favourite moment is when George shouts out "Because I have a voice!" Very laconic sentence to express really a lot.

And rehearsing the speech:
LIONEL: Turn the hesitations into pauses,and say to yourself, “God save the King”.
BERTIE: I say that continually, but apparently no one’s listening.
LIONEL: Long pauses are good: they addsolemnity to great occasions.
BERTIE: Then I’m the solemnest king who ever lived.

and

BERTIE: “In this grave hour fuck fuck fuck perhaps the most fateful in our history bugger shit shit (singing)I send to every household of my p-p- The letter‘P’ is always difficult.
LIONEL: Bounce onto it ‘a-peoples both at home and’
BERTIE: “a-peoples both at home and overseas,...”
LIONEL: Beaut.
BERTIE: (singing)“... this message, doo-dah, doodah....spoken with the same depth of feeling...for each one of you as if I were to fuck shit bugger cross your threshold and speak to you mmy - ...”
LIONEL: In your head, now: “I have a right to be bloody well heard!”
BERTIE: Bloody well heard, bloody well heard, bloody well heard myself!

Actually i should put complete movie script here :)