For Helen McMaugh, a 30-year journey has come to an end.

The former Baptist minister convicted of sexually assaulting her in the back seat of a car in 1988 while she was on work experience has been sentenced to prison.

David Benedict Hogg was sentenced in the New South Wales District Court to two years and four months in prison with a non-parole period of 12 months.

Hogg, now aged 65, was the founder of national disability provider Lifestyle Solutions.

It has been the subject of a number of reports of allegations of neglect and abuse of people with a disability in its care.

It was when police first charged Hogg in 2016 with Ms McMaugh's assault that whistleblowers about Hogg's organisation were empowered to come forward.

Earlier this year Ms McMaugh waived her right to anonymity as a victim of sexual assault to speak publicly for the first time about what happened to her.

Helen McMaugh said being betrayed by someone in authority has had a lasting impact on her life. ( ABC News: Chris Taylor )

Hogg, who pleaded not guilty, was found guilty at trial of digitally penetrating Ms McMaugh in 1988 when she was aged 16.

The court heard Hogg, then 35, drove the school girl to a secluded carpark under the southern pylon of the Harbour Bridge.

Then a married father-of-three, he encouraged Ms McMaugh to confide in her before launching himself at her, kissing her, putting his hands in her pants and digitally penetrating her.

Hogg headed multi-million dollar charity Lifestyle Solutions for more than a decade and before that had a successful career with Mission Australia.

Lifestyle Solutions cared for 1,200 adults with a disability and 300 foster children in group homes across the country.

During the trial, the court heard that Hogg was a Baptist youth minister, who was the former school chaplain at Carlingford High, in Sydney's north-west, when he took Ms McMaugh and her schoolmate on work experience to work with juvenile offenders and homeless youth.

At his trial, Hogg acknowledged he took the schoolgirl on a Friday night drive to counsel her but denied her took her to the Harbour Bridge and denied touching her at all.

Hogg, who continues to maintain his innocence, claimed he was watching football at the house of another girl's family.

His solicitor Hugo Aston said his client would launch an appeal on all grounds.

For her Year 11 work experience, Ms McMaugh arranged to shadow Hogg as he did his work for NSW Family and Community Services. ( Supplied )

In sentencing Hogg, Judge Antony Townsend said the victim Ms McMaugh was only 16 and one month when the assault happened.

"The courts have long since recognised the long-term harm suffered by child sexual abuse victims, which is partly applicable seeing as the victim had just turned 16," Judge Townsend said.

He described Hogg's behaviour in driving Ms McMaugh to a secluded car park under the Harbour Bridge as "well-considered" and "not a spontaneous act".

"The offence involved a breach of trust," he said.

"All too often members of the community who hold positions of trust breach that trust."

Judge Townsend said he had to sentence Hogg based on the laws at the time, when the maximum sentence was eight years.

Ms McMaugh said the assault had been a 30-year sentence on her, but despite this felt the judgment was fair.

She cried as the sentence was handed down.

"I'm very appreciative of the judge and his ruling," Ms McMaugh said.

"It's been three years now since I wrote my statement so it's been a long three years and a difficult process but it's really good to come out the other end.

"Now that it's been dealt with I feel satisfied. I feel heard, I feel vindicated and David Hogg can face the repercussions of his actions.

"I can put this aside and move on with my life. It's really been all encompassing. I want to spend some quality time with my family. I'm even thinking about going back to study."

She said the assault had affected all levels of her life, including her family and her own self-confidence.

"My motivation has always been the safety of children. When I found out he was running Lifestyle Solutions I was mortified. It's comforting to know that at least now he won't be able to work with children again," she said.

"I do believe whoever the perpetrator is, victims should come forward and speak to police."

The trial included evidence from Ms McMaugh's school friend, Jamie Parker, who is now a Greens MP in NSW.

Ms McMaugh confided in Mr Parker at the time, who then informed his mother who went to the school, and this was given in evidence during the case.

Greens MP for Balmain Jamie Parker gave evidence at the trial. ( AAP: Joel Carrett )

The NSW Baptist Church said Hogg had not been a minister since 2007.

Lifestyle Solutions said it had new systems in place and was continuing to work with regulators on reforms.