Chelsea boot vs balmoral

Chelsea boot

noun
  • An elastic-sided ankle boot. 

balmoral

noun
  • A Scottish cap with a flat top and a plume but no brim; a blue bonnet. 

  • A heavy walking shoe. 

  • A figured woollen petticoat. 

  • An Oxford shoe. 

How often have the words Chelsea boot and balmoral occurred in a corpus of books? (source: Google Ngram Viewer )