Julia Gillard's ex-partner convicted of sexual assault

Mathieson met his victim in 2020 when they were walking their dogs and the pair struck up a friendship, the court was told.

On March 13, 2022 the woman invited Mathieson over for dinner at her Brunswick East home and the pair drank wine before watching a documentary on her lounge and falling asleep.

The woman woke up to see Mathieson sucking on her nipple while he cupped her breast with his hand.

When she told Mathieson "don't do that" and pushed him away, he kept trying to put his mouth back on her breast before she ordered him to get out.

The woman confronted Mathieson about his behaviour the following day and he apologised, saying , "that won't happen again", before she reported the assault to police 10 days later.

She moved interstate within weeks after feeling unsafe in her home and afraid Mathieson would come back. 

The attack rendered the woman completely confused after she made it clear to him she didn't want more than a friendship, she said.

"I felt like the friendship was a lie and I had not been heard," the woman said in a victim impact statement read aloud to the court.

"I was in a state of confusion, anger and feeling completely disrespected."

The woman said she dealt with an eating disorder along with anxiety and feelings of distrust - particularly towards men - after the assault.

The interstate move took a toll on her work and she ultimately relocated overseas to have her family's support and feel safer, she said.

Mathieson's lawyer Brad Penno pushed for his client to be spared a conviction, noting his remorse and unclear recollection of the assault.

Mathieson remembered the incident as "involving affection and cuddling", and regarded his relationship with the woman as close and intimate after they spent time together at both their homes.

However, it was clear the victim was not interested in an exclusive sexual relationship with him, Mr Penno said.

Magistrate Belinda Franjic said his assault was serious and suggested it warranted a conviction.

"It's a particularly intimate form of sexual assault," she said.

"What I'm sentencing for is an episode where a woman is asleep in her own home when ... (she) wakes up and sees a (person) she trusted sucking on her breast."

A fortnight after the assault, Ms Gillard told the Adelaide Advertiser the couple had split more than a year earlier.

She and Mathieson, a former hairdresser, were together for a decade and lived at the The Lodge and Kirribilli House throughout Ms Gillard's three-year term as prime minister.

Mr Penno on Thursday said the former prime minister met his client, "a talented and creative hairdresser who made an impression", in 2004.

Their relationship was impacted by the COVID-19 pandemic after Ms Gillard was given a posting in London.