Royal fumble for Abbott

"Ma'am" as in ham, not "ma'am" like palm.

Prime Minister Tony Abbott did not take heed of the line made famous by the film The King's Speech when referring to Catherine, Duchess of Cambridge, in Canberra on Thursday.

"Your grace and warmth, Ma'am, have been abundantly on display," Mr Abbott said in a nod to the duchess's efforts during her Australian visit.

While the slip might have left sticklers aghast, but it didn't seem to faze Kate.

In the 2010 film starring Australian Geoffrey Rush as King George VI's speech therapist, then Queen Elizabeth instructs Rush's character: "It's 'Your Majesty' the first time. After that, it's 'ma'am', as in 'ham'. Not 'ma'am', as in 'palm'".

Opposition Leader Bill Shorten followed protocol, referring to "her royal highness".