The work depicts an Aboriginal youth trapped in a television, symbolising slanted and racialised media coverage, with one hand extending from the old box set holding a phone to denote the power of social media.

"One of the big issues in that mural is that 50 per cent of the children in prison are Aboriginal and yet only three per cent of the population in Australia are Aboriginal," Mr Guider says.

"That's unheard of and it's an international embarrassment".

The former bank robber, 68, is acutely qualified to comment on incarceration rates after spending six years in Long Bay - one of the country's best-known jails - in his 20s.

Charting a traumatic personal journey marred by molestation as a youngster, Mr Guider is also keenly attuned to the horrors of being detained as a child and the long-term deleterious impacts it can sustain.

"Children's prison hardens you, it brutalises you," he says.

"The worst thing that they do when they put a child into children's prison is that they're removing them from the only people who love them".

Yet his experience in Sydney's Melrose Boys Home, which he says later translated into a life of crime, did not detract from his love and passion for making art for over three decades.

Trained at the National Art School, Mr Guider hasn't followed the traditional path of acclaimed artists exhibiting in galleries.

His work has garnered international attention, though, including a gold medal for two large light installations he exhibited in the 2017 Florence Biennale Contemporary Art Award.

But he prefers the public to engage and interpret his outdoor paintings, which, at their core, are socially conscious.

"The public response is my recognition," he says. "It's my life-long love, creating artworks."

While in 'The Bay', Mr Guider pleaded with his jailers to let him to paint four massive murals on the prison's walls using scaffolding.

Nearly four decades later, the ethereal and colourful works he created between 1986 and 1988 remain under heritage orders.

"There's images of freedom in them," he says, describing naturalistic and futuristic elements of Aboriginal resistance from flying robots to towering trees.

Mr Guider's artistic and political journey set him distinctly apart from his half-brother Michael Guider, whom he has publicly condemned following convictions for paedophilia and manslaughter.

Elsewhere, he holds a special interest in the social construction of language and its "slippages" by politicians.

Showing off his latest mural at Petersham, Mr Guider points to the text emblazoned on the wall - "The subtle violence of social silence" - as a call to arms to interrogate how language is sanitised when it comes to incarceration.

"For example, children's prisons sounded really bad so governments changed it to use detention centres or detention, like in school," he explains.

"And then they changed the word youth because that was too painful as well and now they're juvenile justice centres.

"You can call it a justice system as much as you like but it does not change the fact that you're putting children in prison.

"That's the reality and through words, socially, we hide the pain of that reality from ourselves by changing these words."

Active during the sweeping global Black Lives Matters protests after the death of African-American George Floyd, Mr Guider feels it was a time of social change which galvanised communities under pandemic lockdown.

"What I'm doing ... in a small way, where I'm putting things on the wall, is that it will make people ask questions," he offers.

His concerns come in the wake of an agreement by Australia's attorneys-general to raise the age of criminal responsibility from 10 to 12.

The decision, last November, was in response to pressure from more than 30 United Nations countries.

Several weeks later, the First Peoples' Assembly of Victoria wrote to state Attorney-General Jaclyn Symes, urging her to legislate the age be raised to 14.

The ACT government has moved to go with 14 years, while the same change is planned for Tasmania and South Australia.

NSW Greens MP David Shoebridge also introduced a bill late last year calling for the age to be raised to 14 and for alternatives to prison to be considered for under 16s.

"At ages 10 and 11 children are still losing their baby teeth, they don't have their pen licences let alone driver's licences," he said at the time.

Australian Associated Press