Could somebody explain this construct.
He worked like a horse, did Walker.
***** NOT A TEACHER *****
(1) What an interesting question.
(2) I think (ONLY think) that some people would prefer this order:
He worked like a horse, Walker did.
(3) Your question sent me to my books, which explain this as a
(a) That is, some unnecessary words that you use to make the statement more dramatic.
(i) Your sentence is: He worked like a horse.
(a) You then make it more emphatic and clearer by repeating what you said and adding his name: Walker did (work like a horse).
(4) My book gives this famous pleonasm from Shakespeare:
To be or not to be, that is the question.
(5) When you diagram the sentence, the pleonasm is considered an independent element.
(a) Grammatically speaking, it does not "modify" any particular word in the sentence. In other words, it refers to the whole sentence.
You are a good student, you are. Have a nice day.