Britain's Prince Harry has earned a kiss and a marriage proposal - his third from the same Australian superfan - during a walkabout in Sydney.

Hundreds gathered at the city's famous Opera House to greet the prince as he came to the end of a month-long attachment with the Australian Defence Force (ADF).

He spent more than half an hour meeting schoolchildren and shaking hands with fans, some holding signs which read "Marry me Harry," "His Royal Hotness" and "Gingers Rule".

Victoria McRae (21) wore a sequinned Australian flag dress and a plastic gold tiara and held up a sign which read: "Marry Me Prince Harry - Last Chance!".

After getting the chance to pop the question in person, she grabbed the prince round the neck and surprised him with a kiss - to the delight of the crowds.

Harry, dressed in his military uniform, told her he would "have to think about that", and then bit his knuckles.

'I'll have to think about that' - Prince Harry in Sydney | Image: Mark Metcalfe/Getty Images

The student said: "I got to kiss him. And I got to kiss the premier, who I didn't know was the premier."

"I got Harry's lips, I only got the premier on the cheek."

Ms McRae told reporters she had kayaked into Sydney Harbour with a sign popping the question in 2013 and also asked Prince William to pass on her proposal during his tour of the country last year.

Another fan, Anne Woods, gave Harry a stuffed koala for his new niece Princess Charlotte, but while he thanked her, he said he wanted to keep it for himself.

"It was just lovely, just lovely to give him a gift for all the charity work (the Prince does)," she said.

Before meeting the crowds, he took part in a military exercise in Sydney harbour.

While Harry has been away, William and Kate's daughter, Charlotte Elizabeth Diana, was born on May 2nd.

The prince, who moved down to fifth in line to the throne following the baby's arrival, described his niece as "absolutely beautiful" and said he could not wait to meet her.