Two writers

I once tried to collaborate with someone in writing a play. I had, what I thought to be, a good plot about an MP ambitious for high office who is found to have been involved in some nefarious activity whilst serving in The Falklands campaign. I wrote the first scene and sent it to my collaborator, a once well known actress. She liked it.... up to a point. The wife of the MP was, she said, not right. An actress would not want to play the part: she was too miserable, she moaned a lot about her life - she was too damned miserable.
I re-wrote it putting in lines my collaborator had suggested but it didn't work.
The play never took off. We abandoned the project.
I recall what the American theatre critic and academic, Eric Bentley, wrote about collaboration between playwrights: "The play by two authors is two plays - and therefore, by the odd arithmetic of the theatre, less than one."