The Secret Life of a Mystery Writer

In the later version, in the red signal, Sir Alington West is a much bigger character. He actually appears at the dinner party at the Trent's. And after this party, he has an argument with his nephew, Dermot. Christie uses this argument for purposes of a misdirection that is entirely absent from the early version of the story. It shows her early in her career honing her skills as a mystery writer.