half-crown vs sixpence

half-crown

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

sixpence

noun
  • A former British coin worth sixpence, first minted in 1551. 

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