By Peter Hunt
BBC royal correspondent in Australia
The "r" word has not been mentioned during the Queen's tour of Australia, either at the endless receptions or during the countless speeches which are part and parcel of a foreign royal tour.
But the issue of whether Australia will one day finally sever its ties with Britain and become a republic has been brought to the fore once again by the mere presence of the Queen.
The Queen is generally held in high regard in Australia
She's visiting a vast country - for the first time in four years - where's she's the constitutional head of state.
As far as monarchists are concerned, the matter was settled pretty decisively back in 1999. Then, voters, in a referendum, overwhelmingly rejected the idea of a president being elected by parliamentarians.
A system created in its colonial past, lives on into the 21st century. For the supporters of the status quo, the maxim, "if it ain't broke why fix it?" seems very appropriate.
Seven years after the referendum, the debate about the rights and wrongs of a republic is not an active political one. Those impatient for change have chosen not to protest during this tour, not least because it might prove counter-productive.
It was an unrepeatable tour which prompted the young monarch to declare at the end that she was 'sad to be leaving the shores of your wonderful land'
The Queen is generally held in high regard here, even by those wishing to move on.
But Australia has changed dramatically since the Queen first came here in 1954. Then, most Australians still viewed the UK as the mother country.
In the days before television was such a dominant force, they turned out in their millions to see her.
It was an unrepeatable tour which prompted the young monarch to declare at the end that she was "sad to be leaving the shores of your wonderful land".
In the decades since, the ethnic make-up of the country has become more diverse and the importance of the British crown in everyday life has been greatly reduced.
'Tentative time frame'
There have been two developments in the past few days which have hinted, just hinted, at change.
First, there were the comments of staunchly monarchist Prime Minister John Howard.
Australian Prime Minister John Howard is a staunch royalist
In a BBC interview, he said: "I don't believe Australia will become a republic while the Queen is on the throne. Beyond that, I don't know".
He went on to insist he wasn't suggesting Australia might not accept Charles as their king. But his words do provide a tentative time-frame for when the link could be broken.
It's a possibility that's bound to have occurred to the Prince's advisers.
At the moment, when he fulfils his destiny in Britain, realms which were once happy to have the Queen might begin to have second thoughts about her son.
Then, at a state banquet, Australia's Queen delivered a speech which her aides had toiled long and hard over and which they regarded as significant and strong.
In parts it read like a mother talking at a child's coming of age party.
The theme was the maturing of Australia as a nation. The Queen spoke of "taking this opportunity to reaffirm my confidence in the future of this great country".
What was left unsaid was what, if any, role the British head of state would have in that future. Her advisers have always insisted she's relaxed about what future course Australia might choose to take.
For republicans, change is inevitable.
They cling to the belief that no new Australian monarchists are being born.
They would view the two developments I've highlighted as the start of the long goodbye.
They accept it could take time, given their Queen's robust health.
One of their supporters has spotted a potential fly in the ointment for them.
She thinks the biggest risk to their cause would be if Prince William found his future wife in an Australian pub.