After four months he left to get back to the United Kingdom - exhibiting a desire to get on that can be traced to when his accountant father died from a brain aneurism, when Dr Coleman was just 11.
"It does shape your attitudes to life, and it probably makes you realise at a young age that you have got to make the most of the time that you've got and get on and do some stuff, set some priorities but get on with life and keep moving forward," he said.
The three Coleman boys were sent from Meadowbank as out-of-zone students to Auckland Grammar - where the future MP became head prefect - and their mother, a teacher herself, placed "huge emphasis" on education as a way to get ahead.
"My mother made it very clear that was how me and my brothers were going to progress and it worked for us," said Dr Coleman, 49, whose brothers work as lawyers in London, one as a Queen's Counsel.
In 2005, the then-38-year-old captured Northcote from Labour MP Ann Hartley - the only seat National took off the Government in any of the four main centres.
A misstep came the next year when, as National's associate health spokesman, he made headlines for smoking a cigar in British American Tobacco's corporate box at a U2 concert.
There were reports that Dr Coleman had been punched after he allegedly blew cigar smoke at a woman. He disputes that account.
John Key, newly appointed as the opposition leader, backed the first-term MP, saying he would not play "mother hen" to his MPs.
Dr Coleman, who studied medicine at Auckland University, has now been Health Minister for nearly a year, having stepped into big shoes when Tony Ryall retired from politics at the last election.
Despite holding one of the most important portfolios in Government, he has maintained a relatively low public profile.
Mr Ryall's tenure was noted for his colourful shirt and tie combos, but also stability which saw changes introduced without controversy.
Dr Coleman soon stamped his mark by dumping the cost-cutting agency Health Benefits Ltd (HBL), which Ryall had defended despite it being unpopular.
The Association of Salaried Medical Specialists commented at the time that "sometimes a change in minister without a change in government can be as significant as a change in government".
The union's executive director, Ian Powell, now tells the Herald that statement no longer applies. The Health Minister, like his predecessor, had failed to follow through on promises to give doctors greater leadership, Mr Powell said.
A refresh of the Health Strategy, a document which sets the strategic direction for the sector, will be watched closely.
A key priority will be to move patients away from hospitals and have them treated closer to home at medical centres, many of which are privately owned.
Another challenge is to reduce the burden of chronic conditions, particularly obesity. Measures are being put to Cabinet and will be made public in a couple of months.
Dr Coleman has already ruled out taxes on sugar or products such as soft drinks.
A graduate of London Business School's MBA programme and former PwC consultant, he believes consumer demand will see the food industry lower sugar, fat and salt content without regulation.
Overseas, recent advertisements have warned mothers "your child is what you eat", with one viral campaign by Brazil's Pediatric Society of Rio Grande featuring a poster showing a mother breastfeeding, with a burger painted on her breast.
Such campaigns could be seen here, Dr Coleman said.
"It is things around maternal nutrition, how healthy people are around the time of conception and during early pregnancy [and] avoiding ... diabetes that comes specifically during pregnancy."
Getting kids off the couch is also part of the plan. On the personal front, Dr Coleman coaches his 5-year-old son's soccer team and attends most of his daughter's netball games on Saturdays.
Sports memorabilia line a wall of his Beehive office, and Dr Coleman's other role as Sports Minister is clearly not a burden (he cited the All Black ethos in his maiden speech and hosted their RWC team naming).
Along from Jack Lovelock's framed black singlet and an original photo of the Invincibles All Blacks team - picked-up in Otahuhu by his late father for 50c - there's a gift from his time as Defence Minister.
The painting depicts Kiwi soldiers in a fire-fight on the roof of Kabul's InterContinental Hotel, and Dr Coleman is near his most animated in explaining the back-story. There's also a flash of low-key ambition.
"I loved defence actually and dealing with defence personnel was an absolute highlight ... [but] the PM asked me to do health, and if I wanted to continue up the tree, that was the logical next move."
Opposition jousts make for compelling duel
Exchanges between Jonathan Coleman and Labour's deputy leader and health spokeswoman Annette King have become compelling.
That's not for the fireworks. Dr Coleman's repeated taunt that Ms King sent cancer patients to Australia during her time as Health Minister ensures there is real feeling.
But his flat, croaky delivery and penchant for citing statistics ensures questioning rarely boils over.
There is pressure, however. Ms King has highlighted a string of negative health stories in the media, a recent example about cuts to home-help for the elderly.
Other attack lines have included patients waiting in the hallways of Dunedin Hospital, and people sent back to their GP without a specialist assessment.
Health funding has fallen in real terms, Ms King said, and those pressures meant Dr Coleman will fail to keep a lid on the portfolio.
"What Coleman faces is the $1.7 billion that is missing in the health budget ... you can't constantly not meet the cost pressures in health without it bubbling over."
Ms King queried her opponents' vision and enthusiasm: "There is a slightly bored approach to him".
Dr Coleman said negative stories were a long-standing reality of the portfolio, and cited statistics (17 in the interview) to underline why National's spending is working.
"We are doing 50,000 more operations per year.
"There are 110,000 more specialist appointments per year, 5500 more doctors ... it is hard to say that we are not doing more."
