Diminutive in stature, with neatly combed hair and wire-rimmed glasses, he casts a long shadow as he walks between rows of empty chairs to the clerk's table.

After 37 years serving in three parliaments, the deputy clerk and serjeant-at-arms will retire on January 31.

He has helped generations of politicians navigate the convoluted parliamentary procedures that would make most Australians' heads spin, and has been a source of frank, assured advice for many a fledging parliamentarian and journalist.

From bumping into pollies in the loo, to even being mistaken for one by former prime minister John Howard, Mr Kiermaier has had an unvarnished look at the halls of power and those who roam them.

"I've sort of been that proverbial fly-on-the-wall," Mr Kiermaier said.

When Mr Kiermaier accepted his job at the Assembly in 2003, he headed along to question time to try and get a sense of the place.

Mr Kiermaier had worked at the Old Parliament House since 1980, and New Parliament House since 1988, so he was accustomed to the theatrics but the content surprised him.

"I had been used to on The Hill question times talking about the invasion of Afghanistan and things like that. Then I hear the questions about buses and bus stops," he laughed.

"That really brought it home to me that it's a very local assembly, very different."

While he witnessed the blitzing reform of the Hawke and Keating years, the monumental upheaval of the Howard era and the epic power struggle that engulfed Rudd and Gillard's reign, Mr Keirmaier believes it is what happens in this building on London Circuit that has the most profound impact on Canberrans' lives.

"A lot of people tend to not really understand what the Assembly does or put down its importance but you leave here in the afternoon and you drive on the roads which are to do with the Assembly, you take the bus or your bike or you go pick your kids up from schools and again it's the Assembly," Mr Kiermaier said.

"A lot of people tend to disregard or not fully appreciate that."

The Assembly runs "off the smell of an oily rag" and its parliamentarians are "very young", but Mr Keirmaier said he has been impressed by the hard work and grassroots campaigning of the ACT's lawmakers.

"You're always loathe to compare Assemblies with other Assemblies, it's a bit like comparing football teams or players of different eras together but I do believe this Assembly, the composition, and I'm talking on both sides, there are actually some very talented people there, very enthusiastic people, and they're quite keen to do right by their constituents, by all people in the ACT," Mr Kiermaier said.

Ever the consummate public servant, Mr Keirmeyer won't nominate favourites but says Wayne Berry was the most "enigmatic" member he remembers.

"He was your typical poacher turned gamekeeper," Mr Keirmaier said.

"He was the member who had been suspended the most but he was also the person who had suspended the most when he was speaker.

"He's the only member to my knowledge who's crossed the floor, he voted against his own party and he's the only member [as speaker] to have chucked a chief minister out."

Former deputy chief minister Simon Corbell was also fun to watch in action, Mr Keirmaier said.

"He fully understood all of the procedural acts and knew how to use them."

Mr Keirmaier will fondly remember John Howard's Christmas parties, scuttling between the Senate and House of Representatives in Old Parliament House in high rooftop corridors few will ever wander, and laying on the lawn of New Parliament House after a long night's sitting.

He won't miss the Legislative Assembly debating the budget until 5am, although they have not done that for a few years now, he conceded.

In his retirement Mr Keirmaier would like to volunteer at Old Parliament House, now the Museum of Australian Democracy, where he hopes some of the "ghosts" from years gone by will keep him company.