Harding - who won the 2001 Archibald Prize for a portrait of John Bell as King Lear - was at the National Portrait Gallery on Friday to talk about his exhibition Nicholas Harding: 28 Portraits which is on display until November 26. Curated by Dr Sarah Engledow, it features works in a range of media including oil paintings of actor Hugo Weaving and writer Robert Drewe, gouache paintings of Harding's mother-in-law Edie Watkins and actress Anna Volska, and spur-of-the-moment drawings of airline passengers drawn on refuse and airsick bags.

Harding, a self-taught artist, said he began drawing people when he was at school. When he was 15 he drew portraits of his fellow students and teachers: the former reacted with gusto, but the response of the staff was mixed.

"Some of them were rather displeased with my depiction of them in what we might call an unempathic and reckless adolescent way," he said.

"I've since learned empathy has a large part to play in the painting of portraits of people. Looking back, I'm a little bit embarrassed by my lack of sensitivity."

As an adult, he worked as an animator for many years, finding some of the skills there such as brevity were usefully applied to his simultaneous pursuit of painting. He painted landscapes and still lifes, developing his knowledge and technique before moving into portraiture in the early 1990s.

His 2006 portrait Robert Drewe (in the swell) took a lot of work.

"There were two failed attempts to get that portrait right," he said.

He worked for a long time from sketches, photos and memory trying to capture a fleeting expression until he was finally satisfied.

Harding said that while he was occasionally commissioned to paint a portrait, most of the time he approached his subjects to paint their portraits because he admired them - they were labours of love.

Engledow said while this was Harding's first solo exhibition at the National Portrait Gallery, his work had featured in three previous shows she had worked on including The Popular Pet Show which finished earlier this year.

She said his portraits were "glorious, so vivid and evocative" and said "he is very attuned to the very small gestures and expressions that are the distinctive marks of a person's personality".

Nicholas Harding: 28 Portraits is on at the National Portrait Gallery until November 26. portrait.gov.au.