Those who know him well will tell you that Steven Marshall beat himself up about the “Vote Labor” gaffe on election eve. After a campaign with so few missteps, here was a doozy right when the spotlight was at its fiercest.

Given one seat – a handful of votes the other way in any given marginal – could have been enough to end 12 years of Labor rule, the implications of the slip have prompted plenty of “sliding doors” ruminations.

But it was another campaign gaffe that Labor has seized on with increasingly gleeful vigour in the months since.

It came more than a month out from polling day, lost amid an appearance at a Property Council lunch.

Marshall was being grilled by a panel of political observers: one asked which social issues motivated the respective party leaders.

Marshall replied: “To be quite honest, I didn’t go into politics for the social issues.”

It made a ripple, albeit a minor one, in the campaign, but it has for Labor become a potent brush with which to tar the second-term Opposition Leader as an arid accountant, a businessman with no head nor time for matters beyond the economy.

And it shows no sign of letting up.

In September, fledgling Transport Minister Stephen Mullighan digressed from a parliamentary answer to chide: “Is that something you are interested in — social issues now, is it — Leader of the Opposition?”

A month later, Treasurer Tom Koutsantonis lashed out: “Well, we are in politics for the social issues. We are in politics because we care about working people.”

Outgoing Education Minister Jennifer Rankine, too, filibustered an answer to inquiries on education cuts from Liberal shadow David Pisoni by retorting: “I am surprised even that the shadow spokesperson would ask a question like this, being that they clearly have a view that their policies, or their leader, were certainly not in politics for social issues.”

Even now, Marshall concedes the question threw him.

“My answer was that I didn’t come into politics on a single cause, or a narrow range of causes; I didn’t come on a narrow social agenda … but I think the people of SA can make up their own mind on Steven Marshall,” he tells InDaily.

“I think I’ve been able to demonstrate in my time in parliament that I can deal with a range of issues; some of those would certainly fall under a social agenda.”

One of those is a bill designed to provide compensation to members of the Aboriginal ‘stolen generations’. Marshall finds a new gear when he discusses it; there is a distinct sense that its passage has become a personal mission.

“It was the Liberal Party that actually introduced legislation to pay compensation to those people affected by what became known as stolen generations,” he explains.

“It’s extremely difficult from Opposition, because the Opposition can’t create money bills so we had to be careful the way we constructed it.”

But he says the only alternative to the framework the Liberals devised is for individual claimants to take legal action against Government.

“That’s extremely expensive for Government and for the person who takes the action, and it’s inappropriate I think to ask members of the stolen generation who have been disenfranchised to take action against the Government in the twilight years of their life,” Marshall says.

The bill has now passed the Legislative Council, with crossbench support, but it appears doomed in the Lower House. But Marshall decries what he calls Labor’s “very adversarial approach”.

“What I’ve been disappointed in is the Weatherill Government, despite their public statements of interest in our first peoples here in SA, haven’t even tried to engage with the Opposition whatsoever on the Stolen Generations Compensation Bill,” he says.

“The minister (Ian Hunter) wasn’t present in the chamber during the debate on the bill, which is extraordinarily disrespectful.”

Instead, Labor MLC Tung Ngo spoke to the bill as chair of the Aboriginal Lands Parliamentary Standing Committee.

Ngo said in a statement to InDaily the Government “recognises the pain and suffering of members of the Stolen Generation”.

“We remain committed to working to address the ongoing impacts experienced by members of the stolen generations, their families and communities including through the provision of funding.”

Marshall’s zeal hasn’t sprung overnight: he’s travelled to the Anangu Pitjantjatjara Yankunytjatjara Lands every year since becoming an MP in 2010.

“Quite frankly the conditions they live in are shameful,” he says, immediately animated again.

“Anangu are absolutely wonderful people and live in an incredibly sacred and beautiful part of the state, but the governance arrangements in the APY Lands are nothing short of dysfunctional, and nothing’s been done … as far as this Government’s concerned, it’s out of sight out of mind.”

He derides a “procession of Government ministers flying in and flying out, opening vegetable gardens and not grappling with the devastating problems that exist on the lands”.

While the Labor side has been relentless in exploiting Marshall’s “social issues” own-goal, Greens MLC Tammy Franks says the leader’s social conscience should be recognised.

“Quite frankly, I don’t think Steven understood the implications of the answer because he’s not a politician by trade, and that’s to his failing,” she says.

“He’s a politician now, so he needs to understand the implications of that question.”

She says Marshall has “a real commitment to Aboriginal affairs”.

“He’s the only member that stuck it out with the Reconciliation Board (Marshall has been the Liberal representative to the board for the past six years) and he’s seen at least four ALP members come and go on that board,” she says.

Franks’ explanation is not that Marshall is bored by social issues, though she concedes he doesn’t share her own passion for policy solutions to issues like euthanasia or legalising sex work.

But rather, “I think he doesn’t understand the power of symbolism … that politics of a narrative that Weatherill is expert at and the Labor Party is really good at”.

“It’s to his failing but that doesn’t mean he doesn’t do social issues – he does.”

And he does proudly, if over-exuberantly. When challenged on his self-professed disinterest in social issues, he reels off a list of examples, dating back to childhood.

He won a Centenary of Federation medal for disability services – “well before I had any aspirations for politics” – and was a Prime Minister’s Employer of the Year winner “for employing people in SA who were living with a disability”. He was once nominated for South Australian of the Year in the environment category.

“It’s not like I’ve just picked one hobby horse and given it a good belting; since I was a kid involved in a range of projects … I was a cub?” he offers hopefully, if humourously.

The challenge for Marshall now is to marshal his own troops after successive election defeats; but he insists that doesn’t mean a bitch-and-block approach to parliamentary engagement.

“Certainly with any sensible bill the Government puts forward I’ve tried to work extraordinarily cooperatively with them,” he says, pointing to WorkCover reform by way of example, a change “long overdue that needed expeditious passage through the house”.

The bill’s author, John Rau, even singled Marshall out for thanks after it was passed last October:

“The Leader of the Opposition has been very positive and very engaged in this process (and) the first thanks that I wish to place on the record is to the Leader of the Opposition … for the very constructive way in which you have engaged on this very important project. If the success of this project turns out to be what I really believe it will be, that success, by reason of your behaviour, is as much your success and the whole parliament’s success as it is the government’s success.”

But it won’t be all bipartisan backslapping.

“I think the most significant problem facing SA is an incompetent Government which doesn’t understand how we generate an economy and create jobs for the next generation,” Marshall says, snapping back into party-political mode. He knows these words by rote, but one senses he believes them too.

“I don’t apologise for focusing my attack on the Government on those areas, it doesn’t diminish my attack for poor performance on a range of social areas,” he says, reeling off child protection, a “fairer deal for the Anangu” and small business, before quickly realising that small business doesn’t really fall into the category of “social issues”.

“The Government received 36 per cent of the vote at the election, they managed to form minority government and have all the arrogance of a Government which won a landslide victory; it fails to consult effectively with the Liberal Party, it fails to consult with the crossbenchers and it fails to consult with the community,” he says.

I put it to him that the Government’s electoral success and subsequent manner might be as much a reflection of a poor Opposition.

“Yeah, well, of course the leader ultimately has to take responsibility for the performance of the party, whether that’s good or bad.”

And which is it?

“Well, I think it’s been a combination … there were many disappointments in 2014, but we’re a very united, and strong and focussed Opposition, and we’ll do everything we can to hold the Government to account.”

On Saturday, he finally, narrowly tasted electoral success – his first as Liberal leader. It wasn’t much, but it was a start.

He’ll next face off against Weatherill again at Business SA’s “Back To Business” event at the Convention Centre this Thursday. Marshall will be making his standard argument on economic management, but it’s unlikely he’ll again shun his social conscience.

“I’ll put my social credentials up against the Government’s at any point,” he says.