Is the word "robins" in the text below a metaphor and if so what does it stand for? The only robin found in dictionaries are birds.
"The king was in the habit of filling high posts with men of no [titled] account so that he might, if the fancy took him, dismiss them as he would a valet." The men treated like valets in fact were robins, at the top of the bourgeoisie.
— Richard Sennett, Respect in a World of Inequality, Penguin, p.71.