In front of a scrum of international media in the gardens of Government House, Princess Mary's son Christian proved he was like any other two year old, and threw a tantrum.

The family had agreed to pose for the cameras once in return for privacy on the rest of their Sydney visit, and obligingly took a short walk around the well-manicured garden at 11am today.

A precise route had been planned by their minders from the Royal House of Denmark. Princess Mary, Crown Prince Frederik and their children Christian and Isabella, 17 months, would walk once around the lavish fountain, down the garden path, briefly pause with the Opera House in the background and then walk back inside.

It all went well until dad, who had been carrying Christian, decided the toddler could walk the last leg of the tour by himself.

As soon as he was put down on his feet, the little boy burst into tears, stuck his thumb in his mouth and sat down hard on the ground, refusing to move.

His father, under fire from dozens of flashing paparazzi lenses, scooped up the child and whisked him away.

It was a swift end to what was otherwise a fairly relaxed display of family life by the royals.

Though Prince Frederik was characteristically short on words with the media, Princess Mary chatted happily about their trip in Australia.

"Its been wonderful catching up with family and friends," she said.

"Christian's English is getting better ... it's important for the children to see the land where I grew up."

She even translated her son's Danish, when he started yelling by the side of the fountain.

"He thinks there's sharks in there," she said.

The cherubic young princess Isabella cooed at the cameras throughout the walk, even managing a little wave at the end before the family went inside.

The family are on the last leg of their Australian tour and are due to return to Copenhagen in the coming days.