For a few days in mid-June, Hague found himself surrounded by the largest media scrum in the Parliament building lobby as he made his biggest political impression in his four years as an MP, attacking the Accident Compensation Corporation for a series of failures.
"There aren't many barometers for how well you're doing in this role," Hague says.
But hundreds of supportive emails for ACC claimants, and his spokesman role for ACC issues suggested he was building a reputation as a competent member of Parliament.
"Unless you get that external validation," he said, "you start to doubt your own judgment about whether you're doing the right things or not."
ACC's downfall - which included the demotion of minister Nick Smith and the departure of its chief, chairman and three board members - was prompted by exposure of the corporation's treatment of patient Bronwyn Pullar.
But the shakeup was partly the result of quiet, dogged persistence by Hague, who has been challenging ACC's "culture of disentitlement" since 2009.
His higher profile during the debate capped a good couple of months for the MP.
In May, Meridian Energy backed down on its plans to dam the Mohikinui River, which ran through Hague's home territory on the West Coast.
He had campaigned against the hydro-electricity project in his previous term as Greens' conservation spokesman.
In his Wellington office, where New Scientist magazines sit next to a framed picture of him flexing his biceps for gay magazine Express, Hague told the Weekend Herald his political streak kicked in at age 12.
An earnest, "self-obsessed" child, he formed an anti-pollution group at his school in Aldershot, England. He belonged to a youth bird-watching society and loved books.
His office bookshelf features mostly non-fiction - Al Gore's An Inconvenient Truth, mountain biking guides, Treaty of Waitangi history, whereas at home, he reads Scandinavian thrillers.
His father, a building inspector, and mother, an accounting assistant, moved the family to New Zealand when he was 13.
Aged 16, he joined the students' council at Hamilton Boys' High School and took on the headmaster, successfully demanding a referendum to restore a house system to the school.
His lifetime of campaigning was sparked at Auckland University, where his studies in maths and physics were overshadowed by the protests of the late 1970s and early 1980s: the Bastion Point occupation, the Springbok Tour, and Homosexual Law Reform.
He joined Young National because he was motivated by ideas of "individual liberty and freedom" but soon quit because he felt this was a misguided goal when "people started from different points".
Hague did not do things by halves. When he later became interested in Scandinavian countries because of their progressive politics, he learnt Swedish to understand them better. Then Norwegian and a little Danish.
In 1981, he threw himself into the protests against apartheid during the South African rugby side's New Zealand tour, failing most of his university papers as a result. Attending major protests twice a week, he was arrested 10 times.
He was knocked out by a policeman while in a "sleeper" hold, and again by a police baton outside the final test match at Eden Park. He suffered minor, but permanent nerve damage in one of his hands after a policeman handcuffed him too aggressively in Gisborne.
"I had started the year with the intention of studying ... but the reality was [the tour] became totally consuming.
Despite further arrests for being drunk in public as a student and for an anti-sexism protest at a Miss Universe competition, he has just two convictions, for trespassing. He invaded the pitch at the Waikato rugby ground in 1981 and occupied the office of Aerolineas Argentinas in 1985, the airline taking the All Blacks to South Africa.
So how did the Springbok tour compare to present-day political protest?
"It has been a long time since we've had anything that has polarised people and has been an issue on which people felt so strongly that they had to become involved."
Hague said more New Zealanders opposed asset sales in 2012 than people who opposed apartheid in 1985.
But he does not expect a similar groundswell around asset sales. He believed the public's sense of engagement with politics had diminished, and voters felt they had less leverage over the political process. This was evident in the lowest-ever turnout of eligible voters in the 2011 general election.
Hague did not think a protest the scale of Springbok tour would be repeated: "It's really hard to imagine now."
His participation in the public unrest in the mid-1980s coincided with internal conflict over his sexuality.
At first believing he was bisexual in his late teens, he began to "come out" as gay in his early 20s. "It was an environment where there was essentially no role models. The assumption of heterosexuality was so strong ... it took a long time for me to get to the point of realising I was gay."
Thirty years on, he is still "coming out".
"You encounter people most days who don't know and so assume that you're heterosexual and have to go through the whole thing. In your mind, you think 'can I be bothered ... do I need to tell this person?' So, in a sense, it's never over."
Hague, 52, met his partner, Ian, in 1984 at an All Blacks match against Scotland at Eden Park, where they were protesting the New Zealand side's plan to tour South Africa the following year.
Like many other Green MPs, he had lived on Waiheke Island, where he ran a bookstore, then left for the West Coast when it became suburbanised.
He feels his life as a gay man is much better than in the 1970s, but for teenagers questioning their sexuality today, New Zealand is not much different.
"When I speak with youth groups about who the role models might be for gay teenagers, usually the best they can come up with is Kurt from [American TV show] Glee and [Shortland Street character] Ellen. It's better than it used to be, but not by much."
Along with Labour MP Louisa Wall, he has submitted a private member's bill to legalise same-sex marriage.
But for now, his focus is on reforming ACC. New ACC Minister Judith Collins has agreed to sit down with him to hear his 12-point plan to turn around the corporation, and even paid respect to his tireless efforts in the House.
Hague admits he may finally be getting noticed. "And it's not coverage for an expenses scandal or some error that I've made but for exactly the political issues that I'm promoting. So that feels like a validation."
