John, or Iain, was born in 1893, the son of fisherman Norman MacCuish and Rebecca MacCusbic of Backhill. When John was 7 years old, his father obtained 19 Borve, one of the newly assigned crofts that replaced Borve Farm, to which the family moved.  

John attended Berneray School from 1899. During the Great War he was killed  whilst serving in the Royal Naval Reserve as a deckhand on HM Trawler Cantatrice. The trawler was sunk by a mine, with all hands lost.