Can't tell you, my boy. Strictly confidential.
5 seconds sound clip from the The Remains of the Day movie soundboard.
You can hear this line at 01:42:47 in the Blu-ray version of the movie.
Quote context
[...]
- I'm still thinking about it.
- I thought you should be informed of the situation.
- Yes, thank you. That's most kind of you.
- Well, I trust you'll have a most pleasant evening. Thank you.
- Is something special tonight, sir? Your visitors tonight, are they special?
- Can't tell you, my boy. Strictly confidential.
- So I can't sit in on it, then?
- Well, whatever it is that gonna take place tonight.
- Once you've had your food, you'd better make yourself scarce.
- Well, it sounds pretty special to me.
- Good evening, Prime Minister. How are you?
[...]