A gentleman can't do that. It isn't correct.
5 seconds sound clip from the The Invincible Armour movie soundboard.
You can hear this line at 01:21:21 in the DVD version of the movie.
Quote context
[...]
- But if I could get to the court, perhaps I could clear myself.
- Huh, you wouldn't live that long.
- If you let me go, how will you explain yourself?
- A gentleman can't do that. It isn't correct.
- Now you saved my life twice. I won't forget and we'll meet again. Goodbye.
- Well, the Minister sent me. He knew that you'd probably take this shortcut.
[...]