A 77-year-old wartime diary has been reunited with the family of its late owner after being found on the floor of a supermarket in Australia.

Margo Cooper died in March 2011 but her diary, written about her time in the Women's Auxiliary Air Force in 1943, was discovered on the ground in a shop in Gordon, Sydney.

The collection of poems and photographs was handed to Kuring-Gai Police on May 20, sparking a nationwide hunt to find Mrs. Cooper's family.

Her daughter Rosie Gibson, who lives almost 400km (249 miles) away in Dubbo, on the other side of New South Wales (NSW), said it felt like she had “won the lottery" when police returned the diary to her.

The diary was reunited with its owner's daughter Rosie Gibson, center (NSW Police)

“I can't get over how beautifully my mother used to write, and the diary is in such good condition," she said.

“It was just wonderful to get the news on what would have been mum's 98th birthday."

Senior constables Carisa Parker and Colin Mitchell were the NSW Police officers who managed to track down Mrs. Cooper's daughter.

“I was so pleased when we found Rosie – when we called, she was just ecstatic because it was her mum," SC Parker said.

“The day I called Rosie to tell her, it was actually her mum's birthday… she said it was the best birthday present she could have had."

Ms. Gibson said her mother's handwriting was 'beautiful' (NSW Police)

The diary was presented to Ms. Gibson on Thursday by Orana Mid-Western Police District's inspector Natalie Antaw.

“To be able to bring the diary home to her daughters so they could cherish it and see the lovely words their mother had written, that's a very special moment for me as a police officer," inspector Antaw said.