It has been back-to-back meetings for Robertson since moving into Paula Bennett's old office on Monday - incidentally, his 46th birthday - although there is still a bit of furniture-shifting to do.
Bennett had the desk at the wrong end of the office, that much is clear.
Robertson wants it back to where it feels right, where Bill English had it for the eight years he was Finance Minister, as did Michael Cullen, Labour's last Finance Minister.
Robertson also has to set up his office staff.
When Cullen first became Finance Minister in 1999, such was the mistrust that he declined to have anyone from Treasury in his office, although he later accepted one staffer.
Robertson will happily have a Treasury secondee, as well as former Treasury official Craig Renney, who joined his staff in Opposition and helped Robertson to successfully battle National's claim that Labour's fiscal plan had an $11 billion hole.
Treasury is no longer seen as modern Labour's enemy, full of Rogernomes - or what Helen Clark once termed "apostles of the new right".
"They are not going to last long in here if they are," Robertson says. "The Treasury we have in our mind from the late '80s does not exist anymore and that's a good thing."
As well as the meetings, Robertson was guest of honour at a powhiri at Treasury on Wednesday with associate ministers David Parker, David Clark and James Shaw.
"They have their own wharenui on the top floor of the Treasury," Robertson says. "When he worked there, my partner, Alf Kaiwai, was involved in the development of that, so it was nice to be welcomed back in there and spend some time with the staff at Treasury." Kaiwai worked in IT but has since left and drives buses in Wellington.
So what does Robertson thinks makes a good Finance Minister? "I think it is somebody who can hold together the idea of being responsible with the country's finances, being fiscally responsible, with an understanding of outcomes we are trying to achieve for the country," he says.
"And for me, that is about lifting the living standards and wellbeing of New Zealanders. I think you have got to be both.
"If you become too fixated on either, I think you probably won't be achieving all of the things that a Finance Minister should."
Robertson has a big reputation in his party, much more so than his public profile. In two unsuccessful leadership ballots, he won the caucus vote against David Cunliffe in 2013. When Andrew Little won in 2014, Robertson won the caucus and membership vote. Robertson's backers included Cullen and former deputy Annette King.
Jacinda Ardern agreed to stand on Robertson's ticket in 2014 and he remains a close friend - her closest friend and confidant in politics, says King.
Robertson, Ardern and Hipkins worked in the back rooms of the Clark-Cullen Government - although Robertson was the more senior in terms of age and Beehive experience - and the three were all voted in together in the class of 2008.
Robertson held the shadow finance portfolio for only three years - after David Parker turned down former leader Andrew Little to continue in the role.
King, Little's former deputy, says Robertson was the natural choice to become finance spokesman after Parker.
"Grant has got a big brain. He has got the intellect, he has got the political nous with his colleagues, he is very well liked, and he also knows how to manage. He has got the ability to say yes and no." He had also worked hard to gain credibility with the business community.
"They couldn't fault his ability to take on issues and understand them and make decisions," says King.
Robertson himself says he has had good practice in the past three years of saying no to colleagues as he developed Labour's fiscal plan - as he will have to do as Finance Minister.
"There were plenty of ideas out there that people had, that we didn't take up.
"Now, not only are there my colleagues with these ideas, there are armies who work in government ministries and departments who have wonderful and fantastic ideas that they want to take forward too."
But he says he does not want to say no just for the sake of saying no.
He wants Cabinet members to be guided by the need to improve people's well-being.
"That is not just a financial sense. It is also the natural environment we live in, the ways in which our skills improve, our human capital improves, the ways in which our society improves, the way our communities get stronger, if we are using those tools to assess what we are doing then that will answer the question for my colleagues.
"Rather than me be Dr No off the bat, I'd rather get us to a situation where we've got a shared set of understandings of what we are trying to achieve in broader wellbeing outcomes and then that will help my colleagues understand whether that is a good project or not."
He says he has already made Treasury officials aware he is still looking for the most effective, efficient and disciplined spending, "but I want those decisions to be made in that framework of improving living standards."
He also talks positively about Treasury's own efforts to develop what is called a "living standard framework", a way to get officials to think about lifting living standards when making policy.
Robertson knows his political opponents will judge him against this week's employment figures - the final set from National's nine years in office - which showed unemployment down further to 4.6 per cent, 54,000 new jobs and the highest employment rate on record. "They will use that figure politically - it's where we are today," says Robertson.
But he says the underlying fundamentals of the New Zealand economy are not something Labour has challenged.
"What we've challenged is the way in which various groups in society have benefited from the economy that New Zealand has.
"What I want us to do is to focus on the development of a long-term sustainable economy that has high levels of employment and good quality jobs with decent wages.
"That means taking quite a long-term view about productivity, about making sure that wages are keeping up with the cost of living."
Robertson acknowledges confidence is an important economic factor.
"Whether it's a person in a household level or an investor looking to invest in New Zealand or a person starting a business, they need to have some confidence. We have strong underlying settings in the economy," he says.
But he adds: "We have to be wary of not misleading the New Zealand public. If there are issues in the economy, we have to be upfront about those, but we have to show we have got a plan to deal with them."
If the New Zealand economy had continued as it had - growing largely on the basis of rising population and housing speculation, he says, and with rapidly increasing household debt - that was not sustainable.
"It can deliver you some results that appear good but for me, we have to start that transition to an economy that is more productive, more inclusive.
"If we do that, I can remain confident that we can withstand whatever headwinds might come along."
As well as Finance, Robertson became Minister of Sport and Recreation - he is rugby mad and met his partner playing in a gay rugby team. But right now he is not setting a great example of work-life balance.
"I'm intending to improve that," he says. "I have brought my gym gear to work every day and have not gone there yet.
"But this is a very busy time and over time we'll develop up those systems ... I'll give myself a short pass from the gym, but not for long."
