The outgoing chairman of Actew Water and ActewAGL is nothing if not indefatigable.

Even in the midst of the most savage criticism of him during the outrage over Actew Water managing director Mark Sullivan's under-reported $855,000 salary, Mackay maintained his usual joie de vivre.

He emailed The Canberra Times editor-at-large Jack Waterford when the media frenzy over the Sullivan salary had reached fever-pitch, declaring “you pricks have ruined my life" ... with the punchline “bring back The Guardian cryptic crossword!".

And about a month after he had tendered his resignation, surrendering a job he loved, Mackay was hardly languishing, but rather penning a limerick about Skywhale for a 666 ABC Radio competition - and lamenting that he didn't win.

(For history's sake, his entry was:

Skywhale is flying soon,

It's the talk in the local saloon,

But patrons are squawking

And many are baulking,

They say it's a lead bal-loon.)

Mackay simply doesn't seem to get bogged down in the noise and the chatter. He just barrels ahead with a smile on his face. Mr Canberra. Mr Fix It. Mr Can Do.

"I am pretty positive. Incurable. My mum taught me the concept of serendipity and it's always sort of stuck with me a bit. I'm definitely glass half full and I always feel I'm luckier than anyone else," he says.

His resignation from the helm of the boards of Canberra's water and power utilities takes effect on June 30. His farewell is on June 27 at the visitors' centre at the National Arboretum Canberra. Just “his closest friends" – “about 300 people".

He is feeling sadness and “a little disappointment in how it all came about".

"But my overwhelming feelings are of gratitude, because I've had the best job in Australia for 15 years, and considerable pride with what we've achieved in that 15-year period," he said.

Mackay, 62, tendered his resignation in April when the Actew board met with its two shareholders, Chief Minister Katy Gallagher and Treasurer Andrew Barr over the Sullivan salary affair.

Mackay said Gallagher and Barr were “really angry" and the meeting was “very tense".

He understood the anger. Actew had under-reported Mr Sullivan's salary by $234,000 in an annual report and a letter to shareholders in 2011, both stating his remuneration package was $621,171. It was five months before the mistake was corrected and shareholders informed.

Mackay's take on what the politicians' attitudes were ran from “Mark was paid miles too much bloody money and what the hell were we doing?". He said the government eventually accepted Actew had been “incompetent rather than conspirators".

"Clearly, I had to take a large part of the responsibility for what had occurred, I thought that was reasonable. I'd signed a letter to them and it said this was the guy's salary and it was wrong," he said.

Did he know when he signed the letter the numbers were wrong?

“No, absolutely not."

Mackay maintains he wasn't pushed but something had to be done.

“I'd signed the letter, I was the chairman. There was a storm we just couldn't put a lid on, like you can most things."

Mr Mackay said the money spent on salaries and corporate sponsorship was negligible when the return to the government was taken into account.

"We've probably put back to the ACT government in the time I've been here in current dollar terms, two billion dollars," he said. "So this is not a mickey mouse, little sleepy monopoly utility which is what a lot of people want to think it is. It's a very, very large company by any stretch of the imagination. And if you want to do what we're doing, you've got to pay people well. And I don't limit that to the CEOs, that's right down the organisation."

The Sullivan salary controversy shows the ends Mackay will go to Fix It.

A former Canberran of the Year, Mackay is a man of extraordinary influence with connections throughout the national capital. He has been or remains a director of numerous boards including the Canberra Raiders, Koomarri, the Canberra Glassworks and the National Arboretum. He is chancellor of the University of Canberra. He knows how to rally the troops and raise the money. He has unashamedly used his profile and connections to get things done, to mine the resources of the top end of town.

Former chief minister Jon Stanhope cited Mackay as one of his closest allies during his decade in power. Mackay says in the early days of the arboretum, Stanhope asked Mackay to “share some of the misery" and help take some of the heat out of the then controversial project while talking it up. He did so heartily and has become the face of the facility as the chairman of its board.

He has opened doors, tugged on coats, lent on his contacts to raise money for organisations such as Camp Quality, Calvary Hospital, the Salvation Army and the Canberra Cancerians. In 2009, he persuaded a consortium of Canberra businesses in 10 days to raise the $220,000 needed to re-sign Canberra Capitals star Lauren Jackson (including money from Actew, ActewAGL and TransACT).

He happily says he used the resources of ActewAGL and Actew to promote other causes.

"I have been in a very high-profile job and I think I've tried to use that profile for good things," he said.

“It occurred to me I could be the CEO of this big company and just literally entirely inwardly focused or I could use my profile and the resources available to me to help out a whole stack of other organisations.

“So, people like Koomarri or the Salvation Army or the Glassworks. I didn't just go in there and chair their boards. I got the whole company [involved]. So ActewAGL processes the payroll, does all the audits for the Canberra Glassworks. ActewAGL fixed all the IT for Koomarri. ActewAGL gave one of its surplus vehicles to the Salvos. So I've tried as best I could to use that profile and particularly the resources."

Mackay says there was no falling out with Stanhope over who got the credit for the arboretum, saying he made sure to say first up at its official opening in February that without Stanhope there would have been no arboretum.

But Mackay said the two did often lock horns over the project.

“He was totally focused on the trees and I was totally focused on the tourism and visitor stuff," Mackay said.

“ At the extreme I reckon you could have a fantastic time up there if there were no trees at all and he would say I think you'd have a fantastic time up there if there was none of the infrastructure. So we sort of philosophically interested in different things and we had some very robust exchanges about those. He would hop into me about, 'Why aren't you looking after the trees properly and what the hell are you doing all this other stuff?' and I would say, 'The other stuff is really, really important'."

Mackay says he is a compassionate person and that has influenced the way he has treated staff to strangers.

Two of his younger brothers, David and Stephen, died within six weeks of each other due to AIDS in the late 1980s. Mackay is the oldest son in a family of six children.

“I was working for [federal minister] Stewart West at the time and it was a really, really busy job under Hawke and Keating. So apart from being sad that I was about to lose my brothers, my role was to prop mum up and keep her going and I did that as best I could.

“It was a very sad time, my mum was living alone in a little country town by herself. My brother was one of the first 10 people in Australia diagnosed so it was seen as a punishment from God for taking drugs or being homosexual."

The son of a stock and station agent from Wellington in country NSW, Mackay arrived in Canberra in 1969 to work as a clerk in the statistics section of the Immigration Department.

His journey up the career ladder of the public service including general manager of the Overseas Property Group (managing Australia's embassies in 70 countries), senior private secretary to Administrative Services minister Stewart West in the Hawke government, director of the Australian Protective Service and deputy secretary of the Department of Finance and Administration.

He joined Actew in 1998 as the chief executive and then performed the same role at ActewAGL between 2000 and 2008. He has been chair of Actew and ActewAGL since 2008.

Mackay will remain in Canberra with wife Colette and their family. He'll continue to serve as the chair of the arboretum and a director of the Raiders, Little Company of Mary Healthcare, CIC Australia, Australian Satellite Communications and Datapod Pty Ltd.

"I don't have any plan to retire ever. I plan to work until I can't work any more," he said.

In his surprisingly small office in ActewAGL House with paintings of south coast hideaway Mossy Point on the wall, Mr Mackay says helping to set up ActewAGL in 2000 was his biggest achievement.

“My greatest legacy will be ActewAGL," he said.

“It's turned out to be the most successful utility in Australia, we still have the cheapest electricity prices which I'm very, very proud of. We have the best customer service in Australia, independently benchmarked. We have the happiest staff, the most reliable supply and a very, very successful joint venture."

He is also proud of helping to create TransAct in Canberra at a time when he says Optus and Telstra were “treating Canberra like Boggabri" as they instead raced each other for broadband business in Sydney and Melbourne. And the way ActewAGL responded in the wake of the 2003 Canberra firestorm to restore power and water remains a source of great pride.

His greatest regret was his part as chair of the board in Koomarri's decision in 2006 to sell the Narrabundah long stay caravan park to a developer who tried, in the end unsuccessfully, to evict the residents. Koomarri, the organisation that provides community and residential services for people with disabilities pocketed $2 million but paid much more in the storm that erupted. Koomarri chief executive Margaret Spalding took her life in 2009 in the midst of a defamation trial against 2CC for comments about her role in the deal.

Mackay said now that he did "everything to undo the sale and to recover some of the reputational damage".

"I also did my best to support Margaret who was really copping it in the media and elsewhere," he said.

“[In early 2009], I sat down with Margaret and we had a very free and easy discussion of where-to-next for Koomarri and what Margaret would do in the future and who would replace her when that day came. A few weeks later she took her own life shortly after a torrid day in court where she had been suing a radio host for defamation over the caravan park fiasco. I still replay our earlier chat and wonder if I could have seen her suicide coming."

The once “wet behind the ears kid" from Wellington says the main ingredient for success is "to work as hard as you possibly can".

"When you're kind of out there having a good time or in trouble or whatever, it's easy to assume that you might have been sitting in your office smoking cigars, well, I can tell you sending our your first email at 3am, which I did on a regular basis, these jobs are pretty tough."

Right now he loves that he can ride his bike to work, be home by six and say “bugger cooking dinner let's go to Kingston". He loves the sport in Canberra, he loves the people, he loves that he can "just about get a day's business done on Mount Ainslie" as politicians, church leaders and business figures take the morning trek up the mountain. Most importantly, he loves being surrounded by family and friends.

"I can't imagine any other city that could have been so good to me and my family," he said.