OFFICIALLY, THE UNION JACK WAS NEW ZEALAND’S SUPERIOR FLAG UNTIL 1965

​NZ FLAG FACT NUMBER 29 

During the early 1960s, an increase in queries to the Department of Internal Affairs about correct use of the Union Jack and the New Zealand flag led to W. A. Glue, Executive Officer of the Historical Publications Branch of Internal Affairs, researching and publishing a booklet titled The New Zealand Ensign. 

Before the booklet was published in 1965, Glue contacted higher authorities in the department about the place of honour accorded to the Union Jack whenever it and the New Zealand ensign were flown together. Glue argued that giving the Union Jack precedence should continue based on the Department of Internal Affairs’ rulings of 1926, 1947 and 1958, to cite but a few. 

I submit that that courtesy should be continued; a change would provoke controversy. It might please a few rugged ‘nationalists’, but I think most New Zealanders (if they notice it at all) would like to see the courtesy continued. It is a mark of respect for the ‘seniority’ of the Union Jack and a mild reminder of our ties within the Commonwealth.
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The Deputy-Secretary and the Secretary of Internal Affairs disagreed, however, with Glue’s position. In his reply to Glue, Department of Internal Affairs Administrator E. T. O’Connor, stated: 
By tradition in New Zealand the Union Jack has always been given precedence over the New Zealand Ensign … The changing status of Commonwealth countries … [means that] most now have their own national flag taking precedence over all other flags, and I feel the same should apply in New Zealand … No publicity should be given, however, to the changeover.

From New Zealand Flag Facts by historian Malcolm Holland. Read more at: 
http://www.silverfernflag.org/press/new-zealand-flag-facts-book