black as Newgate's knocker vs inky

black as Newgate's knocker

adj
  • Completely black in colour. 

inky

adj
  • Of the colour of ink, especially black ink; dark. 

  • Spattered or stained with ink. 

How often have the words black as Newgate's knocker and inky occurred in a corpus of books? (source: Google Ngram Viewer )