Victoria McCrae, Sydney's self-professed "royal tragic", is one of the most persistent women in the Commonwealth after attempting to steal a kiss from Prince Harry during her third proposal to the monarch.

The 21-year-old from Sydney, who has reportedly asked for the prince's hand in marriage three times, reached in to steal a kiss from the most eligible bachelor in the world while he greeted about 500 fans on the steps of the Opera House on Thursday.

Captain Wales, dressed in his British Army combat fatigues and navy beret, granted Ms McRae an intimate audience by leaning in for a peck on the cheek.

The woman, who bears a slight resemblance to the prince's former flames Chelsea Davy and Cressida Bonas, "went in for it" and tried to kiss him on the lips.

"He let me kiss him on the cheek but then I went in for it. The rest was history," she said after the prince called upon his armed forces training with quick thinking and ever quicker reflexes by removing himself from her clutches.

The prince's recent public appearances Down Under have brought the best out of signwriters in the country.

On his arrival in Canberra last month, the strawberry blond prince was impressed with a poster screaming "Red Heads Rule".

In Sydney, Ms McRae's effort was a little too Single White Female for the fifth in line to the throne. "Marry Me Prince Harry. Last Chance!" she wrote.

The super fan also wore a sequin Union Jack mini-dress and accessorised her outfit with a plastic crown.

"It was everything - I'm very happy. I reminded him it was the third time I asked [him to marry me]."

Unlike the time his father, Prince Charles, was accosted by a woman in the surf in Perth, the Harry super fan was not a publicity stunt by the palace.

In 1979, model Jane Priest was recruited by Charles' press team to run up and kiss the future king amid the crashing waves in an effort to shake up his shy, stuffy public image.

Harry, the renowned "Party Prince", has no such PR issue and his minders and security were quick to hose down Ms McRae's affections.

Nine News reported that Ms McRae landed in hot water with police when the prince was last in Australia for the International Fleet Review in 2013.

She then boarded a kayak with her father, carrying another homemade sign that said, "I ❤ U Harry" in an attempt to slip him her phone number.

She was removed from the harbour by police.

Peter King, another long-time royalist who admitted to a small crush, also got to meet the prince where he 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 [a reference to his surname], 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.