sorry J.Bonzo, but Australia was never "part of" Great Britain.
Augsburger is almost correct: the Queen of Australia has other dominions - we are generous enough to share her.
A point of clarification:
the U.K. = United Kingdom, or, in full, the United Kingdom of Great Britain & Northern Ireland.
Great Britain = the sum of England, Wales, and Scotland.
Some people, mostly Welsh & Scots, see Wales & Scotland as being separate countries, but have great difficulty in justifying that view on any basis other than history.
"the only people who are not confused are those who are not paying attention."