And it was a suitcase, tucked away and forgotten in a Tamworth home, that ultimately revealed the story of "who he was".

Doctor Kate Bricknell is Mr Allen's granddaughter-in-law.

She said that case "contained incredible things" and in the lead up to Anzac Day on April 25, she wanted to make sure he was not forgotten.

"We were cleaning out his house when he was moving to the nursing home," she said.

"And my son-in-laws were in the garage and there was a suitcase on top of a cupboard. The boys were throwing things out and they picked it up and said, 'There is something in it'."

When they opened the suitcase, his family found a treasure trove of sporting trophies, his running spikes and singlet, an extensive collection of certificates, championship flags, and so much more.

Dr Bricknell saw the educational potential in the suitcase and decided to coordinate a history project for a group of her students from Crossroads Education.

She said the goal was to help the students develop their research skills, but also to honour and celebrate Stanley's life.

"I wanted them to understand a soldier is not just a soldier," she said.

"A soldier is a person who has a family, hobby, interests, talents and things they wanted to achieve and places they wanted to go, but couldn't because of the war."

Prior to his death in 2022, Mr Allen spoke about his life before and after the war, but never about the 1005 days he served in Australia and internationally.

Determined to uncover more about his life, the students began to investigate his life story, armed with only his name.

Dr Bricknell said they pulled records from the war memorial, interviewed his family and friends, and mapped out his life journey.

"The kids found out things online; they found out things I didn't know, such as how he tried to enlist at 16 in Toowoomba," she said.

"We knew he had two [enlistment] numbers but never knew why, and he never told us ... turns out he toddled off to Queensland to try and enlist. He got all the way through until they found out he was 16 in 1939.

"So he came back to Sydney and had to wait until he was 18 in 1942."

The students compiled his family tree, documented his love of sports until his late age, and found accounts describing him as a "very kind man" who would visit the cemetery every Sunday to talk to his late wife, Eunice.

"Much of the history kids are taught is something that someone else has found out," Dr Bricknell said.

"I wanted the students to have control. I wanted them to focus on the things that made him a person.

"And I wanted them to learn that everyone you learn about in history is a whole person and never defined by that one event."

The kids found Mr Allen's life "quite interesting and complex".

Mr Allen's childhood in Sydney was "loving, but quite impoverished".

"He grew up in Surry Hills, behind Central Station, and he would tell stories about going to the razor gang leader Kate Leigh's Christmas Party," Dr Bricknell said.

"He would talk about how, in the depression, he would stand in the queues for food, and tell horrific stories of what school was like. He left school at 14 years old."

And if not for a horrible stroke of luck, he would have competed in the Olympic Games.

"He had tripped on his shoelace; he came third in the qualifying race and the other two went off to compete," she said.

"He talked a little bit about his running, but it was back in the day when you didn't have coaching or strappers."

But there always seemed to be a "gap".

On his return from Papua New Guinea, Mr Allen was hospitalised with PTSD [post-traumatic stress disorder].

"Over the years, we picked up a little bit of information, but not a lot," Dr Bricknell said.

"The war was part of who he was his whole life, and it was an inescapable part of who he was. I think it is hard for people to understand that a boy went to war and the man carried that with him till three years ago."

Dr Bricknell hopes to continue the Stanley Allen history project with Crossroads Education students going into the future.

"I would like to do it next with high school students and see what they find from the suitcase," she said.

Mr Allen would have turned 100 years old this year.