"Not only could an overweight guy with glasses succeed, but also New Zealand could stand up to world powers hell-bent on destroying each other, and us, in the process," Mr Robertson said.
His political consciousness was further stirred by the introduction of the Employment Contracts Act in 1991. He was working at a supermarket to pay his way through school and university and watched penal rates disappear, conditions go and wages sink.
Mr Robertson went on to campaign against the user-pays ethos in education as student president at Otago University, and then president of the New Zealand University Students Association. He said student politics taught him to stand up for what he believed in.
"After one particularly rowdy but peaceful protest I was accused by a policeman of being the biggest quasi-terrorist in Dunedin. I told him I was trying to lose weight."
Mr Robertson cited the proposition put forward in 1939 by Education Minister Peter Fraser and leading educationalist Clarence Beeby that every citizen, whether rich and poor, town or country, had a right to a free education of the kind best fitted to them.
He said he had come to Parliament to develop this vision for the 21st century.
Mr Robertson's career has included work as a diplomat, representing New Zealand at the United Nations in New York, where he was proud of New Zealand's independent stance that had attracted him as a schoolboy. He has also worked in the Beehive as a senior adviser to former Prime Minister Helen Clark.
Mr Robertson won the politically savvy Wellington Central electorate, dubbing the campaign "Survivor: Wellington Central".
Politics is in his blood as his grandfather Bob Wilkie ran unsuccessfully for Labour in the Wairarapa electorate in 1954 and 1957. Mr Wilkie was in the gallery for Mr Robertson's maiden speech, a day before his 89th birthday.
Mr Robertson saluted the homosexual Labour colleagues who had gone before him, such as Chris Carter, saying their presence had made it easier for other gays and lesbians to aspire to political office.
He said being gay was a part of who he was, as was being a fan of the Ranfurly Shield - currently held by the Wellington Lions. His sexuality had defined his politics "only inasmuch as it has given me an insight into how people can be marginalised and how much I abhor that".
Mr Robertson, 36, said he and his partner of 10 years, Alf Kaiwai, "were living proof it pays not to stereotype".
"We met playing rugby. I was the number eight and he was the halfback - a great combination."
This month the pair swapped vows and rings in a civil union ceremony at Old St Paul's in Wellington.
Mr Robertson says he spends too much time watching sport, particularly rugby and cricket, and still plays a bit of indoor netball and squash.
Mr Robertson won Wellington Central for Labour, beating National's Stephen Franks by 1904 votes. He is Labour's spokesman on state services, associate spokesman on arts, culture and heritage and foreign affairs, and on the government administration select committee.