if we're going to pink nits on this, Pinkerton is usually capitalized, after Allan Pinkerton (died 1884 American detective: private detective). AND proper noun, a noun that designates a particular being or thing, does not take a limiting modifier, and is usually capitalized in English.

I don't think you can call Pinkerton common. even derivatives such as Pinkertonian and Pinkertonism are capitalized.