Sydney-born Heimans, who has painted not only the King but Queen Elizabeth II, Queen Mary of Denmark, Dame Judi Dench, Dame Quentin Bryce and former prime minister Kevin Rudd, humbly hopes the strength of his work speaks for itself.

"I don't do all the parties," he told AAP.

"I'm a busy worker - you will find me alone in my studio almost at all hours."

So busy is Heimans that he's only just about to have his first major exhibition in Australia, at the National Portrait Gallery in Canberra from Friday, with his 2018 portrait of the former Prince of Wales on show.

The painting is set in Dumfries House in Scotland, and depicts the then Prince in a tweed suit by a window holding a walking stick, about to head outside for his regular walk.

"Part of his work routine is to take these walks through the gardens of his various homes because he loves to be close to nature, but also, it's his way of working through the problems of the day," Heimans said.

The portrait is not only a meticulous likeness but a kind of puzzle holding clues for the viewer about the sitter's passions for nature, architecture and art.

Heimans spent a couple of hours in lively discussion with the then Prince of Wales while he was sitting for the picture, and said the chance to show the personal dimension of powerful figures was what fascinated him about portraiture.

The success of the finished painting led to the commission of a giant picture of Queen Elizabeth II for her Diamond Jubilee in 2012, now on permanent display in Westminster Abbey.

But is Heimans ever intimidated by the status of his sitters?

On some level, being Australian helped with this, he said - growing up in an egalitarian society, he's not easily overawed by people of power.

Having spent his career painting royalty and cultural icons such as Dame Judi Dench, Heimans has become a painter of some status, yet it's rare to see his paintings in an exhibition - his last show was six years ago in Denmark.

European art has always appealed to Heimans thanks to his Dutch heritage, and he has been strongly influenced by Rembrandt and the Dutch masters.

Heimans learnt glaze techniques from the 17th century so he could build up layers of colour to create the effects of light and dark.

He studied mathematics and fine arts at the University of Sydney but decided not to learn painting in Australia, instead finding private tuition and travelling to Europe.

There is no trodden path to becoming a portrait painter, he said - like many of his sitters, he has had to forge his way.

Fortunately, Heimans has long had the backing of the National Portrait Gallery, which acquired an early portrait of former High Court Justice Michael Kirby, was instrumental in a commission to paint the former Crown Princess Mary, and holds four of his portraits in its collection.

"I owe an enormous amount to the National Portrait Gallery, so it's extra special that (the exhibition) takes place here," he said.

Ralph Heimans: Portraiture. Power. Influence. is at the National Portrait Gallery in Canberra from Friday until May 27.

Australian Associated Press