Prince Charles has joked he will never again be able to fit into a pair of “budgie smugglers” as he approaches his 70th birthday.

Speaking at an event in Brisbane attended by people celebrating the same milestone this year, the heir to the throne said he knew “only too well” the “strange feeling of disbelief” at reaching that age.

Confessing he did not feel like it was long since his parents were 70, he said: “I do know only too well – and understand – the strange feeling of disbelief that this is actually happening and that never again, for instance, will it be possible to squeeze into a pair of budgie smugglers.

“I don’t know about you, ladies and gentlemen, but now bits of me keep falling off at regular intervals.

“‘Don’t worry’, they keep telling me, ‘you have brilliant genes’.

“But the trouble is I can’t even get into them either!”

Charles, who made the speech at a reception hosted by the Governor of Queensland Paul de Jersey, turns 70 on November 14.

The prince also took the opportunity to speak of his fondness for Australia, which he first visited 52 years ago.

“When I first came to Australia, Australian manhood was partly defined by how many schooners of beer you could line up on the bar – and drink – before the pubs closed early,” he said.

Highlighting once again the challenges facing the environment, he warned that “we are destroying our own life support systems, along with our children’s and grandchildren’s’ future”.

Describing Australia as “an example for us all”, Charles hailed “Aussie values” as a force for good.

He added: “Amidst all this, the Aussie character that is so exemplified by the concept of fairness and ‘fairgo’ is what I believe the world needs so desperately and so urgently – a ‘fairgo’ for people, our planet and for nature herself.”