Rosie Gibson was already thinking about her mum Margo Cooper, on what would have been her 98th birthday, when she got a phone call from police.
Senior Constable Carisa Parker was calling from Kuring-Gai Police Area Command.
"She said 'it's nothing bad, it's nothing bad. It's a beautiful story. She said 'are you Margot Cooper's daughter?' And I said 'yes, I am'."
Mrs Gibson said that moment was like "winning the lottery" for Senior Constable Parker, who had spent months trying to find the next of kin for Mrs Cooper.
Senior Constable Parker was calling to say she had Mrs Cooper's diary from 1943. It detailed her time in the Women's Auxiliary Air Force during World War II.
"I just could hardly believe it. I was in the middle of doing all this cooking and the cooking went out the window for an hour or two," Mrs Gibson said.
"I was already feeling a bit emotional because it was her 98th birthday. I just kept thinking 'where did it come from? Where has it been all this time?'. I was very happy but very puzzled about it all at the time."
Mrs Gibson hadn't known her mum's diary even existed.
It was initially found on the floor of the Gordon Woolworths in Sydney before it was handed into police.
Senior Constable Parker said she had no idea how the diary came to be left on the floor. Her best guess is that it was once left behind when the family moved.
"I'm wondering if maybe they left a treasure box up in the attic and someone was randomly walking around with a World War II diary in their pocket," Senior Constable Parker said.
"I don't know. It's so strange. No one else has come forward to say 'I dropped it'."
However, Senior Constable Parker and Senior Constable Colin Mitchell started tracking down the family.
"It was an absolute treasure. This diary was in remarkable condition and this woman's handwriting was almost like artwork," Senior Constable Parker said.
She was determined the diary shouldn't be given to anyone but Mrs Cooper's family.
A call out on Facebook alerted them to a piece in the Sydney Morning Herald in 1945 about the birth of Mrs Cooper's daughter Rosemary.
From there, Senior Constable Parker used the Registry of Births Deaths and Marriages to find Rosemary's married name. It lead her to Nyngan before a search of Mrs Gibson's licence showed she was currently at Orana Retirement Village in Dubbo.
On Thursday, it was handed over to Mrs Gibson.
Mrs Gibson said she was so thankful to Senior Constable Parker for all of the research she had done trying to track them down.
She said she couldn't wait to read through it.