have a prior engagement vs working

have a prior engagement

working

adj
  • In paid employment. 

  • Enough to allow one to use something. 

  • Used in real life; practical. 

  • Of or relating to employment. 

  • That suffices but requires additional work. 

  • That is or are functioning. 

noun
  • Method of operation. 

  • Becoming full of a vegetable substance. 

  • Operation; action. 

  • The incidental or subsidiary calculations performed in solving an overall problem. 

  • A train movement. 

  • Fermentation. 

  • A place where work is carried on. 

How often have the words have a prior engagement and working occurred in a corpus of books? (source: Google Ngram Viewer )