Mr Green, 56, was reappointed for a five-year term in 2015, but on Tuesday said he would retire in August.

Arriving in Canberra from Ballarat in 1978 to study, he entered the public service as a maintenance clerk at the lower Molonglo water quality control centre in 1981, before joining the Australian Electoral Office in 1982.

He recalls counting the vote for the 1982 election for the ACT House of Assembly advisory body, when he handwrote vote counts on a tally board. Soon after, he helped in a Tasmanian election count where he was astounded to see an abacus used.

But his most complicated count was the first of self-government in 1989, when Mr Green, still with the Australian Electoral Commission, was in charge of counting votes in the "modified d'Hondt" voting system, which he describes as a "mishmash" of two systems arrived at by compromise in the federal parliament. It was so complicated, it took two months to count.

"It was a terrible system, impossible to understand, impossible to explain, and it was full of inconsistencies," he said. "It was really a terrible system."

Labor won five of the 17 seats and pulled together a minority government which lasted only months.

Just ASO6 level in the public service, Mr Green had to front the cameras each day to explain progress. It was a steep learning curve, which he says set him up for becoming the ACT's first full-time commissioner in 1994 (Gary Whitley was the first part-time commissioner).

The first two ACT elections were run by the commonwealth, and Mr Green has run seven elections since as ACT commissioner.

He said one of the good things about the ACT's Hare Clark system was that it produced parliaments that were not dominated by one party. The ACT had only had one majority government since self-government (the 2004 government of Labor's Jon Stanhope).

"I just think that's a healthy thing for parliaments and governments and I think the Assembly has really benefited from that," he said.

But he said the ACT should look again at the size of electorates in future, with seven or nine-member electorates giving a more representative result than five-member electorates.

The ACT had led the country in innovations such as electronic voting and counting, allowing people to apply for a postal vote online, making it easier for people to qualify to make a postal vote and allowing people to vote outside their home electorate.

"A lot of what we've tried to do is make things as user friendly as possible for voters," Mr Green said.

The ACT also had among the tightest laws on disclosure of donations in the country.

Mr Green was supervisor of the vote count for the 1989 Namibian election, the first after Namibia won independence, which he says was a career highlight. He was also National Tally Room manager for the 1990 Commonwealth election and election night adviser to prime minister Bob Hawke in 1984 and opposition leader John Howard in 1987.

Mr Green has been using up leave, with deputy commissioner Rohan Spence acting as electoral commissioner until a new appointment is made.

He has a wife and two children, his daughter still in Canberra and his son living in Glasgow.