Former Trade Minister Tim Groser says he was surprised at how much opposition there was to the Trans-Pacific Partnership (TPP), but believes they had some legitimate concerns which he too shared.
Mr Groser is now a private citizen until he becomes the New Zealand's Ambassador the United States.
He says those attacking the 12-country trade deal had some "legitimate concerns", though much of it in time would "be shown to be an utter hogwash".
"Traditionally, New Zealanders and the two major political parties – Labour and National – have strongly backed trade deals.
"One guy put it to me in Napier recently, 'I just don't get it', he said, 'to argue against TPP is like arguing against good weather and sunshine'," he told the Paul Henry programme this morning.
Mr Groser, also the former Climate Change Issues Minister, says that is exactly how he saw it.
Previously calling the anti-TPP protesters "politically irrelevant", Mr Groser conceded some may have had right to hold concern.
"There are some legitimate concerns out there, many of which I shared as the minister responsible, on things like Pharmac – an outstanding institution that serves New Zealanders tremendously well by very effective method of subsidising very heavily our medicines.
"So there would have been things that caused me a lot of concern, but at the end of the day yes I was surprised how controversial it was."
He did not believe any action would be taken under the Investor-State Dispute Settlement chapter of the agreement, nor would the deal mean anything for Pharmac's independence.
"I don't believe we'll see any of that."
A project he'd been working on for at least 17 years, first as the principal economic adviser for the Ministry of Foreign Affairs and Trade in the late 90s, Mr Groser believed it was a "remarkable coincidence" he was there to sign it off earlier this year.
Though agreed to by the 12 Pacific Rim countries, each respective Parliament needs to sign off the deal.
Mr Groser also represented New Zealand at the landmark COP21 climate change conference in Paris this month, and says one of the most significant things to come out of it was the global research alliance on agricultural emissions.