No other reference has been found to this street apart from one internet forum in which a member noted:
  there was a barracks off Garrison Lane and Little Dartmouth Street that closed in the late 1700'sem>
  
  There is a New Dartmouth Street (1841 census map) referred to in a 1900s A-Z as Lower Dartmouth Street at this location.
  Therefore this has been noted on Guest's Map as Little Dartmouth Street.