Mick Gentleman was elevated to Katy Gallagher's ministry on the weekend, giving Cabinet a solid left majority, with three out of the five Labor ministers in the party's left faction, plus Greens minister Shane Rattenbury, and signalling one of the big battlegrounds of the 2016 election: the suburbs of Tuggeranong.

The Liberals have three of the five Brindabella seats at the moment; both Labor's spots are now held by ministers.

Mr Gentleman was first elected to the Assembly in 2004, encouraged by his colleagues at the Transport Workers Union where he was organiser. He has a long union background as delegate in his many jobs: bank teller, public servant, mechanic, postie, security officer with the Australian Protective Service. Mr Gentleman guarded the offices of prime ministers Bob Hawke and Paul Keating and, such was his love of politics, he took the unpopular shifts to get close to political action, including at the High Court during the Mabo land-rights case.

The son of a telephone technician, Mr Gentleman grew up in a government house in Reid, and says the War Memorial was his playground; in those days winter meant snow and dragging sleds up and down the slopes. His interest in the union movement and social justice began with his parents, he says, recalling the annual union Christmas party where food and gifts his parents couldn't afford at home were laid on. He still has a microscope he got as a gift when he was about six.

Mr Gentleman has lived in Calwell since 1989 and, rather than invite this reporter into his home, he suggested we meet at the Calwell shopping centre. At home, he says, are his two parrots, his two vintage cars including a 1950 Holden bought for the ACT's chief fire officer in 1950, and five motorbikes, including a 1948 BSA. Cars are clearly a love, and Mr Gentlemen has the distinction of ACT rally championships under his belt. He rides as navigator, in what he says is an exhilarating sport that he loves for the adrenalin. And yes, he has had many accidents, including one that left his sternum pointing the wrong way.

Mr Gentleman, who split with his wife in 1993, has three children in their 30s – one son a chef in Adelaide, the other an IT programmer in Sydney, and his daughter a bus driver with ACTION. And with all this interest in transport, you wonder whether that will feature among his ministries when Ms Gallagher allocates portfolios.

Among Mr Gentleman's other passions is the environment. He says he was an instigator of the ACT's feed-in tariff scheme for renewables, and is working to clean-up waterways in Tuggeranong. An issue he wants to push is a "spruce up" for Anketell Street in Tuggeranong.

Labor faces a difficult battle in Tuggeranong, particularly with the big push on light rail and development in the Gungahlin corridor expected to suck demand from the rest of the city. Having lost his seat in 2008 and elected again in 2012, Mr Gentleman says taking the third seat back from the Liberals in 2016 will be a tough fight. But he professes a lack of concern about the Gungahlin tram line, saying he believes the tram will extend to Tuggeranong, albeit in "quite a few years" and, in the meantime, people are happy to hear that it will bring more than 3000 jobs to the city. He is also sold on the transformative message, referring to a visit he made to Freiberg in Germany, where the tram serviced communities of homes that shared one car.

"It's really interesting when you see big efforts happening in the ACT – the arboretum is a really good example. When it began it was quite a difficult sell and Jon Stanhope and John McKay and people like that were the champions for it, and you look at it now and it's wonderful," he said.

He describes himself as a progressive on social issues, such as same-sex marriage and abortion, and has been prominent on abortion debates in the Assembly.