Sydney woman Daphne Dunne, known for being Prince Harry's most devoted fan, has died.

Dunne had been in hospital with a bout of pneumonia for almost two months.

Just last week, she received a letter from The Duke and Duchess of Sussex, Harry and Meghan, congratulating her on turning 99.

The war widow had met Prince Harry three times during his last three visits to Sydney.

While she never did get to have a beer with him, there were always plenty of hugs at their encounters.

It's understood Harry and Meghan are deeply saddened by the news and will be writing to Dunne's family privately.

Play Video Dunne was Prince Harry's biggest fan. Dunne was Prince Harry's biggest fan.

When Harry met Daphne

Dunne got her first royal smooch with Harry in 2015 when he finished a stint with the Australian army.

It was her late husband's war medals, pinned to her outfit, that drew his attention and helped create a special bond between them.

But it was in 2017 that she stole Australia's heart, when she waited for hours in the rain to get another kiss from her prince charming.

Daphne Dunn and Prince Harry meet in 2017. Credit: Dean Lewins / AAP

Her last ever meeting with Harry was six months ago, when she met the Prince and his wife Meghan outside the Sydney Opera House on the first day of the Royal couple's visit to Australia in October 2018.

Dunne had been in hospital with pneumonia when she received a letter from the royal couple to celebrate her 99th Birthday on March 29.

"We'll I'm not out of hospital, but the letter has certainly made me feel better," she told 7NEWS Sydney at the time.

More than just a royal fan

Daphne Dunne on her wedding day Credit: Supplied / The Australian War Memorial

Dunne was not just a fan of the Prince, she was also a devoted wife, mother and grandmother.

Her first husband, Albert Crowne, was posthumously awarded the Victoria Cross. He was killed in action fighting the Japanese in New Guinea at just 24 years of age.

Daphne then married John Patrick Dunne.

Her surviving family told of Dunne's passing in an Instagram post on Tuesday, saying: "It is with the saddest of hearts that I would like to share the news of our most beloved mum and nanna, Daphne Dunne, passed away peacefully yesterday morning.

"She was a truly special lady who will be greatly missed by so many. The simple act of stoping Daphne in the street and holding her hand meant more to Daphne than anyone could imagine."