That's the chairman of the bank, the elder Mr Dawes.
5 seconds sound clip from the Mary Poppins movie soundboard.
You can hear this line at 01:30:13 in the Blu-ray version of the movie.
Quote context
[...]
- These are my children, Mr Dawes. Well, so I assumed. But why are they here?
- They wish to open an account, sir.
- Yes.
- And just how much money do you have, young man?
- Tuppence. But I want it to feed the birds.
- Tuppence? Tuppence? Precisely how I started.
- That's the chairman of the bank, the elder Mr Dawes.
- A giant in the world of finance.
- A giant?
- Uh, Father, these are Banks's children. They want to open an account.
- Oh, they do, do they, boy? Excellent, excellent.
- We can always use... use more money to put to work for the bank, can't we, boy?
[...]