He is a few steps off Cuba Mall-Cuba St, on Ghuznee St, and foot traffic is heavy.
Fortunately, the Otago Daily Times was a few minutes early for the interview as Mr Robertson was running late for lunch at 2.30pm and was ducking off for something to eat.
Although wearing a smart grey suit, the tail of his white shirt was untucked.
He had the air of someone too busy to stop as the campaign was about to enter the final two weeks.
Mr Robertson's day had started early, greeting workers with Labour banners and pamphlets, then door knocking before meeting Finance Minister Michael Cullen for joint campaigning.
"We pick our spots for door knocking through the day, going for areas with an older community or ones with young families."
But it was the street corner meetings where Mr Robertson showed he had remembered some lessons from his university days in Dunedin, such as addressing rallies of students with a megaphone.
In Wellington Central, he has a hit-and-run approach to street corner meetings.
He arrives, turns on the sound system and talks for a few minutes whether six people are attending or none.
Retiring Wellington Central MP Marian Hobbs told Mr Robertson there was always the twitch effect with street corner meetings where people would hear something and peer through their curtains.
Even if they did not venture outside, they were aware of his presence. Winning the seat is no foregone conclusion, he says.
He is up against two particularly strong candidates in former Act New Zealand MP Stephen Franks, who has switched to National, and Green MP Sue Kedgley.
Ms Kedgley traditionally polls around 9% in the electorate vote but the Green party vote in the electorate was the highest in the country at the last election at 17%.
"I know I need some of those Green voters to tick me this time.
''If they can't give me their party vote then I want the electorate vote."
Mr Robertson is well down on the Labour Party list and needs to win the electorate to be sure of entering Parliament.
The same goes for Mr Franks who is low on National's list.
Ms Kedgley is relying on the party vote to return to Parliament and given the latest polling, the Greens could have 10 or 11 MPs after the election.
"When I won the nomination I knew what I was in for.
''This is a Labour-held seat and I should win it.
''I want to be a constituency MP and I am motivated by that desire.
''I have seen Marian work for seven years.
''I know that it takes."
The million dollar question is why someone who seemed to have a successful career in Foreign Affairs would return to New Zealand and work as an adviser for Ms Hobbs, then Prime Minister Helen Clark, as well as working for the University of Otago, in Wellington, to stand for parliament.
"I have been interested in politics for a long time.
''My student political life was advocating to make a difference.
''I want to be in a position to make a difference to the lives of people in New Zealand.
''I think for me that the best way to do that is through Parliament.
"Other people have different areas.
''They could be judges etc.
''That's fine.
''This is what I can do.
''I am a good advocate."
During his time with student politics, Mr Robertson regarded himself as an advocate for students, first in Otago and then at a national level.
When he worked for Foreign Affairs he was advocating on behalf of New Zealand overseas.
He realised that if he became an MP, he would start at the bottom of the rankings and for the former head boy of Kings High School, in Dunedin, it would be like being back as a third former.
The Robertson campaign team was a good mix of enthusiastic young first-time voters and some seasoned long-time Labour activists.
Some public servants were discretely helping him and some friends who had never participated in an election campaign before had volunteered to deliver pamphlets.
The mixture of voters in the electorate had required a range of tactics.
Mr Robertson had a presence on Facebook, MySpace and YouTube to reach younger voters.
Wellington Central had the second highest number of young voters after Dunedin North.
"I have to spend about an hour a day with email.
''There is lots of traffic, some of it nefarious but some of it sincere."
A group of supporters on Twitter had arranged a tweet-up where Twitter users met in person.
About 40 people attended to hear him speak.
He had attended about 25 cottage meetings where people had invited their neighbours in to meet him and speak to him.
His visits ranged from rest-homes to high schools.
There were some strong Labour areas like those in south and west Karori, where door knocking was essential to identify supporting voters.
One of the challenges in standing in a seat like Wellington Central was having to answer technical questions about things like NCEA when he knew there were likely to be two or more people in the audience who worked on NCEA full-time.
It was the same with health issues and the economy.
Public servants abounded in the electorate.
Sitting in Cuba St having coffee as the masses poured past, it seemed a fair distance from where he was brought up.
Asked if he missed Dunedin, Mr Robertson hesitated.
"This is where I have settled.
''I have been here for 14 years, my partner has been here since 1978 and this is where we are.
"I do look back to university in 1993 and see it as a good grounding for what I am doing."
WELLINGTON CENTRAL:
Labour seat held by retiring MP Marian Hobbs.
Main candidates:
Grant Robertson, Labour
Stephen Franks, National
Sue Kedgley, Green Party
The most academically qualified electorate in the country and the second wealthiest.
The Green Party vote is the highest in the country.
Traditionally, the seat has been held by the party in power but former Act New Zealand leader Richard Prebble has held the seat.
