But the marriage equality movement is banking on her as one of its leaders in the same sex marriage debate.

Janine Middleton, 58, a former investment banker at JP Morgan, joined the marriage equality campaign as a full-time volunteer in September 2014 and became co-chair of Australian Marriage Equality (AME) in January 2015.

Her childhood is just as surprising as her background: Mrs Middleton grew up in a housing commission flat in the western suburbs in a single-parent household, where her pro-union, Labor-voting Mum worked in a factory.

She is taking a three-month break from her chief executive role with The Pinnacle Foundation, which awards scholarships to LGBTI students who are marginalised or disadvantaged, to concentrate on campaigning full-time for the “Yes” vote in the marriage law postal survey.

“This is literally seven days a week,” Mrs Middleton said.

Her dedication to the cause led her and husband Shane Daly to become silent electors because of the large amount of hate mail she received at home.

“The hate mail has stopped, but we get the most enormous amount of hate mail at work through our emails — it’s shocking — thousands and thousands of hateful, poisonous emails, with people saying the most terrible threats, physical threats against us,” she said.

“So, the good thing about not being on Facebook is that you don’t get to see the negative things people say about you.

“But, I think it’s part of our community with social media now, that you have these angry people and because they are faceless, they just get on and they spew this absolute hate and poison.

“I feel sorry for them, because I’d hate to have that much hate in my life, but you know, they can say whatever they like about me because I don’t get to see it.”

While Mrs Middleton is disconnected from the internet trolls, she is still very much connected to her religion and is able to balance Catholicism with her pro-marriage equality views.

“I think it’s really easy, I mean, from a teenager, I’ve always believed in God — not necessarily the best churchgoer at times — but to me, it’s a loving God and the God I believe in, I can’t reconcile with someone who would hate people because they were gay or black or different,” she said.

“So, I have trouble understanding why people think that a loving God would actually say, ‘But not you and you’.

“I mean, it just seems funny that they would even think that certain groups would be prohibited from that.

“And I think, as a Catholic, it’s quite interesting, because when we do a lot of polling, when we’re doing these groups and people ask, what age group you are and what religion you are, the two groups that actually support us the most are Catholics and Jews, and I think 72 per cent of Catholics that we poll say that they support us.”

But why did this conservative Mosmanite, who is straight, without any LGBTI family members, decide to surprise most people she knew and become a high profile champion of marriage equality?

The answer begins with Mrs Middleton’s time as a managing director with JP Morgan in London and ends with the public “coming out” of legendary Olympic swimmer Ian Thorpe: that was the turning point, her “line in the sand”.

“When I first started three years ago, no one was talking about marriage equality,” she said.

“I mean, it was really off the radar. When we came back to Australia and I started talking to friends at dinner parties, everyone was, well, they didn’t really have an opinion, they didn’t really care, and were, ‘Why do you care? Because, obviously, you are straight’.

“I think it’s funny, because quite a few people said to me in the early days, ‘Well, what if someone thinks you’re gay?’

“Firstly, if I was worried because they thought I was gay, then I’m kind of in the wrong job!

“But they said to my husband, ‘What if people think your wife’s gay?’ and he was just like, ‘She’s not and I don’t care.’

“Shane is a very down-to-earth Australian man and a man of very few words!”

Mrs Middleton had always had lesbian and gay friends, but only started seriously thinking about marriage equality when she became a manager.

JP Morgan, at the time, was attempting to foster a more open and inclusive culture and hosted LGBTI events such as recruitment activities. But, management was concerned the bank’s attempts were unsuccessful.

Mrs Middleton looked at her own team at the time, which included three gay men. She saw them “edit” their lives — choosing the times and places where they were “out” or acting straight — and wondered how they dealt with such challenges.

Mrs Middleton also had a female colleague at the bank who never acknowledged her sexuality or her female partner in front of others, even as she lay on her deathbed. Mrs Middleton had glimpsed the pair holding hands momentarily in hospital.

Her colleague’s funeral was also “whitewashed”, leaving Mrs Middleton somewhat despondent.

“She never talked about it and she really did try to hide it, because it’s very difficult for people,” she said.

“I’m going back now; it was the anniversary of her death yesterday, actually (October 4); she died seven years ago and even in seven years, things have changed.

“Coming out and being out at work is very difficult for a lot of people because they get judged; they think they’re not going to get the promotion, they’re not going to get the pay rise.

“A lot of people are out at university and then go back into the closet when they get their first job, because they are not confident.

“And that’s why you have a lot of people actually coming out at work in their late 20s and I’ve known people who came out at work in their 40s.

“It’s very difficult, so, I think for her, life was probably just easier to be in the closet, but it’s not really easy, you think it’s easy, but it’s not.”

Mrs Middleton and her husband returned to live in Australia in 2012. Ian Thorpe publicly came out in 2014 and although she had never met the swimmer, she found herself a tearful mess because of the great struggle Thorpe had in deciding to go public.

“When I was being interviewed to volunteer at AME and I started telling my story, I then realised my story was actually a culmination of a whole lot of other people’s stories and Ian Thorpe was the one that really impacted me, to a point where I felt that I had to do something,” she said.

“Having sporting stars supporting marriage equality is phenomenal. If you are a young teenager and you are going through that period in your life and you haven’t told your family yet, you are struggling with it yourself, you haven’t told your friends, but if you see that the NRL, AFL, football, swimmers, Cricket Australia, basketball — if you see all these sports actually supporting you, it makes you feel more included and less isolated. I think that’s an amazing thing.

“I think that’s what the companies do as well, because they think, ‘Well, Mum shops at Woolies and Dad banks at Westpac, and the car is insured with NRMA and all these people support marriage equality’.”

Mrs Middleton, who started the AME program which attracts official support from organisations such as businesses and sporting bodies, believes the support from these sections of the community is sincere and is not about good PR.

“We are up over 2000 (organisations) now — from what I’ve seen, it’s pretty genuine,” she said.

“We’ve actually said to people who’ve come to us, who’ve said they want to sign up, if they don’t have an LGBTI policy, we actually would prefer that they didn’t sign, because we don’t want it being a tick in the box; we want it to be the real thing.”

And Mrs Middleton believes that Mosmanites and other lower north shore residents will vote “Yes” and prove the naysayers, such as Warringah MP Tony Abbott, are a noisy minority.

“I think Mosman will definitely vote ‘Yes’: talking to the women at the gym or at the shops, or wherever, everyone is saying they are going to vote ‘Yes’,” she said.

WHY BUSINESSES ARE TAKING A SAME SEX MARRIAGE STAND

“If you look at Tony Abbott’s electorate, he is the one that is out of step with the electorate, because 70 per cent of his electorate have said that they are supportive and will vote ‘Yes’ (ReachTEL).

“He’s out of step with his own family: his daughter and his sister, of course.

“So, I think Mosman, Cremorne, Neutral Bay — I think this area will be definite ‘Yes’ voters.”

The voluntary Australian Marriage Law Postal Survey closes on November 7.

Visit equalitycampaign.org.au for more information about the campaign.