Mr Horn was born in Palmerston North on 1 September 1917. He was educated at the Nelson Park School, Boys High School in Napier and Victoria University. He graduated LLB and practiced as a barrister and solicitor in New Plymouth (1947-1967). He was Magistrate in Palmerston North (1967-1975). Mr Horn took up his position as Chairman of the Licensing Control Commission in Wellington in August 1975. Jack married Miss Alma Ellen Harkness in 1945 and they have two daughters.