This is part of Noel Coward's Suite in Two Keys and appears on the Noel Coward Collection DVD set.
Paul Scofield, Deborah Kerr, and June Tobin star in this story of a famous writer, Hugo Latymer ((Scofield) who is awaiting a visit from his long-ago lover, Carlotta, played by Kerr. His wife (Tobin) is uneasy about it. However, we learn that her husband says unkind things to her and often isn't nice, and she's learned to live with it. She was once his loyal secretary.
Kerr and Scofield are terrific together. It turns out that Carlotta, an actress, wants to publish their love letters. Then she announces she has a few other letters too.
Hugo suspects she's there to blackmail him, but Carlotta has another agenda.
Now, someone described this as funny. I actually didn't find it so except in the beginning when Scofield is establishing his snobbish character. It's about what we do one another from a lack of compassion, our treatment of people due to our own agendas, repression, and how memory becomes twisted over time.
Sobering and quite good.