errand boy vs go-between

errand boy

noun
  • Someone in a responsible position who performs relatively menial tasks for a senior manager. 

  • A male employed to run errands. 

go-between

noun
  • An intermediary or middleman. 

  • A shogi piece, used in chu shogi and larger shogi variants, that can move one step straight forward or straight backwards. 

How often have the words errand boy and go-between occurred in a corpus of books? (source: Google Ngram Viewer )