Yes, Lord Darlington was among those who tried to make a deal with Hitler.

7 seconds sound clip from the The Remains of the Day movie soundboard.

You can hear this line at 01:20:49 in the Blu-ray version of the movie.

Quote context

[...]

- It wasn't my intention to deceive anyone, sir.

- No need to explain. I can quite see how it happened.

- Darlington. Wasn't there a Lord Darlington involved in all that appeasement business that got us into the war?

- Sorry, sir. I never knew that Lord Darlington.

- My employer's an American gentleman, Mr. Lewis.

- Yes, Lord Darlington was among those who tried to make a deal with Hitler.

- Then, there was a case after the war where he sued a newspaper for libel. The Express, was it? News Chronicle?

- I couldn't say, sir.

- Anyway, he lost.

- He was lucky, really, not to have been tried for treason.

- There it is, just ahead.

- I must confess, I failed to tell you the truth.

[...]