half-crown vs tanner

half-crown

noun
  • A pre-decimal coin used in Britain, Ireland and New Zealand, equivalent to 30 pence or two shillings and six pence. 

tanner

noun
  • A former British coin worth six old pence. 

  • A type of commercially-fished crab, Chionoecetes bairdi or Chionoecetes opilio. 

  • A person whose occupation is to tan hides, or convert them into leather by the use of tan. 

How often have the words half-crown and tanner occurred in a corpus of books? (source: Google Ngram Viewer )