Newgate Knockers: Heavily greased side whiskers curling back to, or over the ears.(http://www.tlucretius.net/Sophie/Castle/… Newgate Knocker: (A). A lock of hair twisted into a curl, usually worn by costermongers and other persons of similar stations in life. So called because it resembles a knocker, and the wearers of it are too often inmates of Newgate. Newgate as a prison is abolished, but many phrases referring to the prison still remain. http://www.infoplease.com/dictionary/bre… Black as a Newgate Knocker A Newgate knocker is the fringe or lock of hair which costermongers and thieves twist back towards the ear. http://www.infoplease.