A crowd of about 500 gathered under the sails of the Sydney Opera House and the Bennelong stairs to welcome Prince Harry, dressed in his combat fatigues, and his official tour guide NSW Premier Mike Baird.

The years 2, 3 and 4 classes from Sydney's St Mary's South Public School were caught unawares while on a school excursion and were treated to a lengthy audience with the now fifth in line to the throne.

An animated prince had the students in stitches and exploded into wolf whistles after a young, albeit brunette, teacher was called up to pose for a cosy photo with their famous guest speaker.

Peter King a long-time royalist got to meet the prince and told him his mother, the late Princess Diana, would have been proud of him.

"He said thank you and had a very firm handshake," he told Fairfax Media.

"I was born a king, I grew up a queen and grew up to meet a handsome prince.

"I now just need to find out where he's going drinking tonight," he laughed.

For his final official engagement of his Australian tour - where he has been embedded with the army in the Northern Territory, far north Western Australia, Perth and at the 6th Aviation Regiment in Sydney - he travelled to western Sydney to meet British Lieutenant Ali Spearing who lost both his legs during combat in the Middle East.

Lieutenant Spearing is in Australia undergoing specialist treatment at the Macquarie University Clinic to fit prosthetic limbs and to learn how to walk again. He belongs to the London District Personally Recovery Unit, an arm of the British military Prince Harry has been working closely with.

He met Lieutenant Spearing alongside Associate Professor Munjed Al Muderis and nursing staff at the clinic and spoke candidly about how he does not want to leave Australia.

The prince also thanked the media for keeping the world informed of his eating habits, a nod to the vast coverage of his many dinners out in Perth, including a takeaway Queen Victoria burger in Fremantle.

He will now travel to New Zealand on Saturday for a seven-day tour where he will visit the national war memorial and take in a Super Rugby match.

The prince will then return to London to meet his new niece, Princess Charlotte Elizabeth Diana.

"She is very beautiful and I can't wait to meet her," he said.