This loyalty was demonstrated in 1957 when he was a pupil at Otago Boys High School and was seen by rector Ted Aim playing rugby for Pirates.
"I was called to his office on the Monday morning and given an ultimatum that if I did not play for the school, I would not play any rugby," Cooper recalled.
"My loyalty was with the club and I left school that day."
Cooper played for Pirates junior teams over the next four years and had reached second grade (the second club team at that time) when he joined the army in 1960.
Cooper rejoined the Pirates club after completing five years of military service and honed his literary skills as a reporter for the Evening Star and a senior subeditor on the Otago Daily Times for 28 years.
"I worked full-time on the book when I retired two years ago," Cooper said.
Cooper's interest in rugby history started in the early 1970s when he was a member of the Otago team that lifted the "Ranfurly Shield of the Air" from North Auckland in 1972, in a sports quiz radio programme.
Writing the Pirates history was a labour of love for Cooper.
It is the fourth club history Cooper has written.
The others were on the Southern Rugby Football Club (1984), the Forbury Park Trotting Club (1988) and the St Clair Golf Club (2005).
Cooper has been commissioned to write the 125th history of the Kaikorai Rugby Football Club for its celebrations next year.
Mark Fowler assisted him with the Pirates project.
Cooper has read most of the sports club histories in New Zealand and believes the Pirates history is one of the the most comprehensive.
"I have written over 100 A4 pages and 80,000 words," Cooper said, "It is three times bigger than the Southern club history I wrote 24 years ago."
There is a detailed chapter on the glory years from 1946 to 1952, when Pirates won three premier banners and produced All Blacks Ray Dalton, Kevin Skinner and Ray Bell.
Another chapter features club guru Charlie Saxton, who played for the All Blacks, captained the Kiwi team after World War 2, coached Otago with Vic Cavanagh and was president and a life member of the New Zealand Rugby Football Union.
