I'm most dreadfully sorry, sir, about what happened at the bank today. I can assure you that...
6 seconds sound clip from the Mary Poppins movie soundboard.
You can hear this line at 01:56:53 in the Blu-ray version of the movie.
Quote context
[...]
- Will you be good enough to explain all this?
- First of all, I would like to make one thing quite clear. Yes?
- I'm most dreadfully sorry, sir, about what happened at the bank today. I can assure you that...
- Yes, Banks. We'll expect you at nine o'clock precisely. Without fail.
- Why, yes, Banks. It's extremely serious.
- We regret this course of action.
[...]