what is the historical significance behind this royal anthem mentioned?
It is the royal anthem in a number of Commonwealth realms, their territories and the British Crown dependencies.
God Save the Queen
"God Save the Queen" (alternatively "God Save the King", depending on the gender of the reigning monarch) is the royal anthem in a number of Commonwealth realms, their territories and the British Crown dependencies. 
when was o canada proclaimed the national anthem 1980 what was it got adopted from? "O Canada" should be designated as the national anthem and "God Save the Queen" as the royal anthem of Canada, one verse from each, in both official languages, to be adopted by parliament.
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God Save the Queen [SEP] Introduction
"God Save the Queen" (alternatively "God Save the King", depending on the gender of the reigning monarch) is the royal anthem in a number of Commonwealth realms, their territories and the British Crown dependencies. The author of the tune is unknown, and it may originate in plainchant; but an attribution to the composer John Bull is sometimes made. "God Save the Queen" is the national anthem of the United Kingdom and one of two national anthems used by New Zealand since 1977, as well as for several of the UK's territories that have their own additional local anthem. It is also the royal anthem – played specifically in the presence of the monarch – of all the aforementioned countries, as well as Australia (since 1984), Canada (since 1980), Barbados and Tuvalu.