At 30, I found out I didn't know my childhood neighbours as well as I thought I did.

This came as a surprise. I grew up wandering in and out of their home as I pleased, and my mum was a freelance journalist, well-practised at sniffing out any stories lurking around.

My parents had moved far from their families to have children, onto a street that was mostly holiday homes, with some retirees thrown in.

Thea and Oswald were a bit of both, and became one set of unofficially adopted grandparents.

But it turns out they didn't just leave their mark on my life - they left one on Australian history.

There would be great excitement when the Austrian couple arrived in Malua Bay from their home in Canberra, even though we'd been swimming in their pool the whole time they were gone.

It had a big fat blue tongue we fed banana and sometimes rescued its babies from the pool filter. It's where I learnt to swim.

The excitement was even greater when their grandchildren arrived.

Sarah and Thomas were much older, and therefore much smarter and cooler, than I was. But they were good natured about letting me tag along with them for card games and trips to the beach.

I remember Oswald bouncing me on his knee, singing a song about horses, and making the clapping sound of their hooves on my feet.

I remember Thea making horseshoe biscuits, and only giving me bananas that were exactly the right amount of ripe.

When I got older, sometimes I would go to stay with them in Canberra. We would go to the theatre and ballet - a special treat for a country kid.

Oswald gave me The Hitchiker's Guide to the Galaxy and sparked a life-long obsession with science fiction and British comedy.

We lost touch over the years, and recently I hoped to track them down.

A quick google brought up results that included the Canberra Museum and Gallery, National Archives of Australia, Trove and the Museum of Applied Arts and Sciences.

It turns out our quiet Austrian neighbours were a slice of history.

The National Archive identifies Oswald as a "Jennings German" - Europeans brought over for the AV Jennings building program in 1951.

The company sought highly skilled tradespeople to spend two years building homes in Canberra, which had to expand from a sleepy country town into the nation's capital.

Many remained in Australia.

Members were involved in the construction of the Telstra Tower, Australian Parliament House, parts of the Australian National University, embassies, schools, shops, churches and countless houses.

Oswald and two friends founded Canberra Furniture Manufacturers. Some of their pieces can still be found in auction houses today.

I'm not sure how Thea and Oswald felt about leaving their families behind. They must have been very young - younger than I am now - when they came here.

I don't know about the challenges and triumphs they faced as they settled in to a new country.

I do know they were unfailingly kind and unfailingly generous, and I treasure the memories I have of them.

Ask people about themselves - even the ones you think you know best. It may turn out that a piece of living history once changed your nappy.