But it was with the Auckland hockey side that he made his biggest impression. During his 13-year tenure, beginning in 1971, he helped establish Auckland as the dominant province in New Zealand hockey, winning the Challenge Shield eight times.
Former Auckland and New Zealand player David Appleby recalls Armstrong's unorthodox coaching style. "He was the coach who didn't coach. Instead, he empowered us as players - he created an environment where we learned to think for ourselves, communicate and share ideas, and work as a team," he says.
Armstrong was "exceptionally proud" of the five Auckland players in the side that won Olympic gold at Montreal in 1976 - Jeff Archibald, Ramesh Patel, Mohan Patel, Greg Dayman and Arthur Parkin.
Off the playing field, Armstrong was a renowned educator. He was the founding principal of Mangere College when it opened in 1971, and over 17 years, built up the school's reputation of being at the forefront of multiculturalism. It was the first New Zealand school not to use corporal punishment.
Armstrong is survived by his wife Joan, three children and six grandchildren.