It did not matter that Yvonne Sillett was the first female corporal in the Australian defence force responsible for training new recruits at the Kapooka army centre in Victoria. Nor did it matter that her work with the Signal Corps managing telecommunications and information systems was respected and valued by her superiors.

What did matter to the Australian defence force at the time was that Sillett is gay. In 1988, when she was 28 years old and had been serving for almost a decade, she was called into an interview and questioned by two commanders.

“It wasn’t an interview, it was an interrogation,” Sillett said. “They said, ‘We know that you’re a homosexual, we’ve been following you.’ I was denying everything but they’d been following me for several months.

“After several hours of this questioning they said they would be taking the matter further and that, based on my sexuality, I could no longer be in Signal Corps as I’d be open to blackmail, and that they were downgrading my security clearance which was needed to do that job. They told me I’d never instruct women again.”

She was ordered to provide the commanders with a list of names of other homosexual personnel, but she refused. Forced from the role she loved and afraid she would be outed, under constant surveillance and treated with contempt, Sillett felt compelled to request her own discharge and left the organisation which she once believed would provide a long-term career.

“I was absolutely shattered,” she said. “I loved what I did, and had been a bit of a trailblazer for women in the army. It was all I had known, and the rug was yanked from under my feet. The trauma I experienced was up there with losing my mother, and there were suicidal thoughts.”

Sillett’s mother knew she was gay and accepted her, but Sillett never told her why she left the army.

Now I’m older and wiser. I know I have nothing to hide or be embarrassed by. Yvonne Sillett

“I didn’t want to break her heart,” she said. “I lost my mum later to melanoma and she died without knowing why I left.”

Sillett is one of 130 former and present defence force personnel identifying as LGBT interviewed as part of research conducted by military academics associate professor Noah Riseman and associate professor Shirleene Robinson. Their work uncovering official historical policy documents and speaking with those affected by the former ban on homosexuals serving prompted them to call for a national apology to LGBT former military personnel.

The researchers also believe a redress scheme should be implemented for those whose careers were cut short and affected by intrusive interrogations and surveillance. This redress could take the form of psychological support, an apology, and in some cases financial compensation. Riseman sent a policy brief to numerous politicians this week urging them to support an apology.

The Greens senators Janet Rice and Peter Whish-Wilson wrote to the prime minister, Scott Morrison, and the defence minister, Christopher Pyne, on Friday supporting the call.

“We write regarding the horrific past discrimination of LGBT service members and their families carried out by the Australian Defence Force,” the letter states.

“A recent report by ACU Associate professor Noah Riseman indicates that LGBT personnel were subject to invasive bodily exams, harrowing interviews that probed intimate personal details and surveillance of movements during and outside of service hours. These practices saw LGBT service members humiliated and intimidated, forcing them to resign their posts or be dishonourably discharged.

Yvonne Sillett’s mother knew she was gay and accepted her, but Sillett never told her why she left the army.

“An apology and redress scheme will send a clear message that the ADF and the commonwealth government condemn these past discriminations and abuses, and to ensure diversity and inclusion continues within the ADF.”

The prime minister’s office did not respond to questions from Guardian Australia, saying it was a matter for defence. A defence spokeswoman said the department was aware of the push for a national apology.

“Defence will review Prof Riseman’s proposal,” she said. “Defence is focused on increasing the diversity and inclusion of its workforce as a critical element of building capability.”

The opposition defence spokesman, Richard Marles, said LGBT people in defence had “obviously been treated pretty poorly in the past”. But he said apologies only worked “when everyone’s on board”.

“We’d obviously be open to hearing more about what’s being proposed, but it’s important that any effort of this kind is explored in an inclusive, bipartisan way,” he said.

Records show between 1953 and 1992 at least 489 men and 165 women were investigated for being LGBT. Data provided to parliament in 1992 on discharges in the five years between 1987 to 1992 revealed 73 honourable discharges of lesbian, gay and bisexual people and 21 dishonourable discharges of LGB people across army, navy and RAAF. November marked 25 years since the ban was lifted on gays, lesbians and bisexuals serving in the Australian Defence Force.

Neil James is the executive director of the Australia Defence Association, which describes itself as an independent, non-partisan, public interest watchdog for defence issues. James said his organisation would not be against a national apology and that it would “probably” achieve something. But he said the Australian defence force should not be blamed for implementing what was policy at the time.

He said considering past events through a modern lens was “a crazy way of looking at things”. He added “there was no point listening to” Riseman, who he described as an “activist” who was “a little emotive about this” issue. He added that he did not believe the historical treatment of LGBT people was “a serious problem in the army and navy” but said it was more of an issue in the airforce, where security matters were investigated by RAAF police who took a more militant approach.

“You also have to look at the era,” he said. “Women weren’t allowed to get married in defence, this wasn’t an unusual situation for the period the alleged persecution was occurring.”

He added that he did not necessarily agree that LGBT people compelled to leave defence because of their sexuality had their careers significantly affected, because he said people at the time didn’t serve for long anyway.

He added it was not homosexuality that defence targeted but the fact homosexuality was a criminal offence. “Because it was a criminal offence people could be blackmailed because they had a secret life and so could be manipulated by a foreign intelligence service,” he said.

But Sillett responded; “Are the Russians really going to care that I’m a gay lady?

“Defence had a duty of care to look after us.”

She recently filed a complaint with the defence ombudsman seeking an apology and compensation, but this claim was rejected.

“The response I received said that what happened to me wasn’t considered serious bullying,” she said. “I was interrogated during my time serving this country. I was followed. These aren’t stories that are made-up. These are people’s lives that have been affected.

“Except now, I’m older and wiser. I know I have nothing to hide or be embarrassed by.”