Painted by one of the country's most significant modernists, Grace Crowley, Painted in grey was exhibited in the 1933 Archibald Prize. But the sitter - who was simply identified as Miss M Roberts - remained unknown.

That was until the artwork was once again hung on the Art Gallery of New South Wales' walls. It was then that it was revealed that it was Marjorie Roberts, a professional artist's model who also sat for Dorrit Black and Arthur Murch in Sydney to support her family during the Great Depression.

But it was just one of the many mysteries that surround Australia's most significant art prize - and Archie 100, which begins its run at the National Portrait Gallery Friday.

While there have been just over 100 years of the Archibald Prize - resulting in more than 6000 artworks - the whereabouts are known for less than 2000 works. And that number is thanks in part to the work of curator Natalie Wilson, and the rest of the Art Gallery of New South Wales team, who have spent the five years before the award's 100th birthday trying to track down as many works as possible.

"I had to put on my Sherlock Holmes cap every day as I went to work and a lot of wonderful works came out of the woodwork, which were fabulous to find," Wilson said

"You unearth these really surprising works. Works such as the one by Violet McInnes, who was the wife of the seven-time and inaugural winner, W.B. McInnes, who put her own career aside as many women of that time did to support her husband and his career and their children.

"But when he died, she took up the brush again and she entered the Archibald Prize with a portrait of a really well-known Melbourne artist and modernist by the name of Sybil Craig, who was one of Australia's first female official war artists."

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Arranged thematically, Archie 100 delves into the controversies and the commonplace, the triumphant and the thwarted, and honours the artists who have made the Archibald Prize the most sought-after accolade in Australian art today.

Each portrait selected for the retrospective offers a glimpse into a specific moment in time, and when presented together gives insight into how society, art and culture have changed since the award first began in 1921.

In that time - and up until the 100th anniversary - there have been 97 winners, with no prize awarded in 1964 and 1980, as well as combined prizes in 1991 and '92. One such winner - and a five-time finalist - is Yvette Coppersmith, who took out the award in 2018 with Self-portrait, after George Lambert.

"I've come to realise that the Archibald is such a unique opportunity for an artist to speak to the whole country, and you really want to be mindful of what is it that you want to speak about, what is it that's important to bring to the forefront of our consciousness, and I feel like that's what I was doing when I did that portrait," Coppersmith said.

"I wanted to speak about progressive women in leadership and bring an expansive idea of younger women in leadership as well so that it would inspire people to maybe see themselves in a way they were not necessarily before. At the time, I was approaching Jacinda Arden ... and there was just this feeling that she was the role model I wanted to bring. And she said she wasn't available to do the portrait, but she was really flattered.

"So I thought it doesn't have to be literal, this is art, so I'm going to channel something of the PM in a self-portrait. And that way, it still can be contextualised and talk about the things that I wanted to speak about."

Archie 100: A Century of the Archibald Prize is at the National Portrait Gallery until January 28.

Think you know the location of an Archibald Prize finalist? Email Archie100@ag.nsw.gov.au

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