Well, something happened last night that convinced me you've been telling the truth.
6 seconds sound clip from the The 39 Steps (1937) classic radio play.
You can hear this line at 00:45:28 in the radio play.
Quote context
[...]
- I suppose you filed the handcuffs.
- No, darling, I picked the lock. I was trying to do the same for you but the file broke.
- Why didn't you leave? You were very anxious to, if I remember correctly.
- Well, something happened last night that convinced me you've been telling the truth.
- May I ask what earthquake caused your mind to work at last?
- No, I hid behind the counter.
- They asked the innkeeper about us.
[...]

 Dead of Night (1945)
 Dead of Night (1945)  Phantom of the Opera (1943)
 Phantom of the Opera (1943)  Scooby-Doo, Where Are You! (1969)
 Scooby-Doo, Where Are You! (1969)  Halloween III: Season of the Witch (1982)
 Halloween III: Season of the Witch (1982)  Knight Rider (1982)
 Knight Rider (1982)