Also, unlike many of her peers, she was consistently prolific. She wrote a novel a year (sometimes more) for over fifty years, plus short stories and plays. Other contemporaries, like Sayers and Berkeley, stopped writing mysteries after WWII.
I'm afraid that all I know is from Green's book. For some reason Christie's producers thought that her version was too experimental or something, so Verner was called in to write a more conventional thriller. I vaguely remember that Green suggested that Christie made some edits, but I'm sorry I can't provide any information outside of Curtain Up.