The New Zealand First Foundation received $100,000 in just one week from two rich-listers, whose donations remained secret because the individual payments fell below the disclosure threshold.
An electoral law specialist says the payments show the level at which donations have to be made public is set much too high.
The Spencers, one of New Zealand's richest families, donated $50,000 to the foundation in July 2017 - election year - using a law firm to make the payments in four amounts below the level at which donations are made public.
The week before, Andrew Bagnall, and entities connected with the racing car driver turned businessman, also donated $50,000 to the foundation in four separate payments.
A law firm acting for the Spencer family, which has a wealth estimated at $1 billion by the NBR Rich List, made four donations of $12,500 each, on the same day - 11 July 2017.
RNZ has seen a letter sent to the foundation by law firm Martelli McKegg that day, confirming that the donations would not be made public.
A Martelli McKegg solicitor wrote to foundation trustee Doug Woolerton saying that, under the firm's understanding of electoral law, the donors must be disclosed to the New Zealand First Party but not publicly declared.
"We understand that as the donations are individually less than the threshold of $15,000 the details of the donors will not be disclosed to the public or the Electoral Commission."
The letter names the four donors as Berridge, Mertsi and Olivia Spencer and Jeffrey Scrimgeour. Records show that each donor was issued a $12,500 receipt by foundation trustee Doug Woolerton.
The Spencer family fortune dates back to the pulp and paper producer Caxton in the late 1800s and today they have business interests around the world. The Spencer property investment company is Clime Asset Management, whose portfolio includes Waiheke vineyard Man O'War.
Members of the Spencer family were named as financial contributors to the National Party in Nicky Hager's 2006 book The Hollow Men.
In the book Hager quotes a 2005 email from former Business Roundtable chairman Rob McLeod to National MPs Don Brash and John Key.
"Berridge and Mertsi Spencer have been talking with me about the possibility of increasing their financial contribution to your election campaign. They are also very keen to meet John after hearing about him from you," McLeod wrote.
There are no records of the Spencer family donating to National in the mid-2000s but electoral donation rules were different then and allowed parties to use trusts to collect money without naming individual donors.
For example, in the 2005 election The Waitematā Trust gathered more than $1.2 million for the National Party but the donors to that trust were not publicly disclosed.
Otago University Law Professor Andrew Geddis, who has viewed foundation documents, believed the 2017 Spencer family donations to the New Zealand First Foundation were within electoral law.
"If four individual family members each individually decide they want to give $12,500 and those four donations are bundled together into one donation of $50,000 and passed over in one amount that's perfectly legal."
But Geddis believed the law should be changed to require greater disclosure. "The ultimate effect is that a political party has received a sum of $50,000 from essentially one family. Now $50,000 in the New Zealand political sphere - it's a reasonably big amount of money."
The donations from Andrew Bagnall were also made in four separate payments. The first was made in his own name on 4 July 2017 for $10,000. Over the next two days, three entities associated with Bagnall made separate payments totalling another $40,000. The payments, from entities named as Miramare, Perune and ETF, all have the same reference: 'election 17'.
Bagnall has been a professional motor racing driver since the 1980s and built his name in business with the Gullivers Travel group.
One of his major investments is Green Cross Health, which owns more than 350 pharmacies under the Unichem and Life Pharmacy brands.
Bagnall, who has a wealth estimated at $125 million by the NBR Rich List, is also a philanthropist and in 2018 donated $1.2 million to establish scholarships for Auckland university graduates.
Neither the Spencer family nor Bagnall responded to requests for comment from RNZ.
The donations are part of a pattern, previously revealed by RNZ, of the foundation receiving payments from wealthy donors just beneath the $15,000 disclosure threshold.
The foundation received 12 payments of $15,000 - one cent under the disclosure level for political donations - in the two years between April 2017 and May 2019, according to records viewed by RNZ.
In that time the foundation received a further six amounts between $14,000 and $15,000.
Those donations alone brought in more than $250,000, yet none of the donors were revealed.
The foundation went on to spend hundreds of thousands of dollars paying bills for New Zealand First, including campaign expenses, renting and setting up a campaign HQ in Wellington and running the party's website.
The Spencers are among multiple large donors to the foundation between 2017 and 2019 revealed by RNZ in recent weeks, where individual payments are $15,000 or less but exceed that in a single year when added together. Others include:
- Cambridge Stud owners Brendan and Jo Lindsay and associated entities: $75,000
- Property development company Conrad Properties and related entities: $55,000
- Business owner and motorsport driver Andrew Bagnall and related entities: $50,000
- Brink's Chicken owners the Van Den Brink family and associated companies: $36,000
- Entities owned by stud owner and former motorsport driver Kent Baigent: $30,000
- Entities owned by rich-lister Graeme Hart: $29,990
- Seafood company Talley's and managing director Sir Peter Talley: $26,950
- Windsor Park stud owners Nelson and Sue Schick and related entities: $20,000