Tom Roberts retrospective at National Gallery of Australia

"A lot of Roberts' paintings are like the Mona Lisa of Australian art and people continue to want to go and see the Mona Lisa," she says of the first Roberts' retrospective in more than 20 years.

"The works coming out of private collections, or works from galleries in Western Australia they will have never seen, so there'll be something new and something old."

The gallery's summer blockbuster show will bring together 133 works including 53 portraits and 53 landscapes, from Roberts' early days studying at London's Royal Academy in 1883 until his death in 1931.

Roberts is seen now as one of the most influential figures of Australian art, as a leader of the Australian impressionists known as the Heidelberg School along with Arthur Streeton, Frederick McCubbin, and Charles Conder.

Painter Arthur Boyd said all Australian paintings were "in some way a homage" to Roberts.

But in his early days as an artist Roberts was seen as a "radical" of the art world, a "cultural warrior" who stood up to the establishment when they criticised the modern, naturalistic style of him and his mates, the gallery's director Gerard Vaughan says.

Although famous for his national narratives and the Big Picture capturing the opening of the first Australian Parliament in 1901, Roberts was a "versatile artist" Gray says.

"[He was] constantly painting different things, city subjects like Allegro con brio: Bourke Street west, we have close-up views of the bush like his painting of The Artists' Camp and then we have pictures looking at the bush from more distant viewpoints some of his more lyrical paintings," she says.

"We've got seaside subjects one at Mentone [in Victoria] and then in London a whole variety of Thames paintings painted in the Whistlerian manner.

"There's such a range in ways of paintings and such a range of subjects that there is in a way so much for many artists to get inspired by."

His friends and fellow Heidelberg School artists learnt much from Roberts, Gray says but those who came after like Fred Williams and later Imants Tillers were also influenced by the way he took the Australian landscape seriously and painted it from his heart.

"Roberts wanted to create images of Australia of today… with his images of Shearing the Rams, it was images of people around him," she says.

And no matter who it was around him the artist seemed to be able to slot in from humble shearers to royalty.

"He was a pretty blokey bloke, he liked camping out, he liked going out and painting shearers he could hang out with the shearers and talk to them… but he could also stay in the big house where the pastoralist was," Vaughan says.

"On the one hand he'd be down at the beach knocking around with fisherman and then go home and smarten up and go to a reception at Government House."

Roberts would have happily devoted his career to grand national narratives, but without wealthy patrons to buy the works portraiture became his bread and butter.

"The cost of buying that huge canvas would be enormous, covering it in expensive oil paint for six or eight months of your life… so he tended to concentrate on portraiture which was a very secure way of earning a living because people always want portraits," Vaughan says.

While Australia's high society recognised Roberts as the best portrait painter they were less keen to embrace work from the country's first radical exhibition of nine inch by five inch paintings he initiated in Melbourne in 1889.

"They sold a lot of them, but they didn't sell them to Melbourne's establishment they sold them to people who were very intellectual, lots of professors from Melbourne university," Vaughan says.

Sydney instead appeared to be more receptive to Roberts and his fellow avant-garde young artists of the 1880s and 1890s while Melbourne remained tied to European model of art.

At the birth of federation Roberts aimed to develop imagery of Australian-ness with his art, Vaughan says.

In 1915 at the age of 59 he enlisted in World War I as an orderly in Wandsworth hospital in London where he became a corporal in the dental department helped with facial reconstruction until 1918.

While other Australian artists painted battle subjects, Roberts never did, Gray says, instead painting soldiers including his son Caleb in uniform was the closest he got to being a war artist.

Abandoning imported shows to put an Australian artist at the centre of the gallery's summer blockbuster is a new approach, Vaughan says, and it's something the gallery will repeat every few years as well as other smaller shows focused on influential Australian artists such as one next year featuring Mike Parr.

After the NGA exported a show of important Australian art to London's Royal Academy of Arts in 2013 Gray feels it's time to showcase and celebrate the country's best at home.

"We've now become of age where we recognise how good Australian art is," she says.

Tom Roberts is on at the National Gallery of Australia from December 4 to March 28, 2016. Tickets are on sale through Ticketek.