I’ve spent the best part of a week trying to find the method behind Malcolm Turnbull’s madness in giving nearly half a billion dollars of taxpayers’ money to a six-person private charity.

The underlying ideology seems to be an attempt to use public funds to leverage a massive effort by corporate Australia into a noble task: saving the Great Barrier Reef.

But that is obscured by the ham-fisted, naive and potentially dangerous way the Prime Minister personally went about the biggest single grant in Australian history.

You’ve got to be completely cack-handed politically to turn the ultimate environmental motherhood statement into something that looks so dodgy.

But that’s Turnbull for you.

One of the peculiarities of this saga is that the Government announced the $444 million donation to the privately run Great Barrier Reef Foundation weeks before the Federal Budget to no criticism.

“As a highly respected philanthropic organisation, the Great Barrier Reef Foundation has a strong fundraising track record, and will seek corporate contributions to further enhance this work,” Turnbull said on April 29.

The grant would fund:

$201 million improving water quality with changed farming practices such as reduced fertiliser use, and adopting new technologies and land management practices.

$100 million harnessing the best science to implement reef restoration and funding science that supports reef resilience and adaptation.

$58 million expanding the fight against the coral-eating crown-of-thorns starfish.

$45 million supporting other work, particularly increasing community engagement such as indigenous knowledge for sea country management, coastal clean-up days and awareness raising.

$40 million for reef health monitoring and reporting to track progress and inform better management.

Even when it appeared as one of the newsworthy items in the Budget there were only muted concerns from some conservation bodies which would obviously have preferred the funding went to them.

But since then, the protests have grown progressively and the matter has been split wide open under scrutiny in the Senate’s environment and communications committee.

The origins of the foundation in 1999 by five captains of business who came up with the idea while waiting for a plane, and its links to some of Australia’s biggest companies, have been intensely scrutinised.

Among the revelations were that the grant came as a shock to the foundation which had not applied for any funds, it was offered to the chairman John Schubert at a meeting with Turnbull and Environment Minister Josh Frydenberg on April 9 with no public servants attending, and the usual tender process was waived.

Labor senator Kristina Keneally has been adopting the time-honoured “follow the money” line of inquiry, revealing that the whole $444 million was paid to the foundation in one lump sum.

One of the witnesses last week was the Australian Conservation Foundation’s economist Matthew Rose, a former Treasury official, who noted the ACF with 70 staff was more than 10 times the size of the Government’s preferred agent for saving the reef.

“Do you accept the key premise for the allocation and the partnership program, which was that the foundation has a track record over the last 10 years of attracting co-investment funds from the private sector and can therefore leverage this $444 million with increased private sector investment in public-good science,” Greens senator Peter Whish-Wilson asked Rose.

“They have links, obviously, to the business community,” Rose said. “They’re business-founded and they have leveraged private investment. I think that is the term that’s used. That’s fine.

“We’re not saying that government and NGOs know best and that we can’t learn something from the business community.”

But then Keneally got to the nub of the issue, asking Rose to draw on his Treasury experience to explain why the money was paid in a lump sum, when it was intended to be spent over six years.

Rose disclosed that the Turnbull Government had promised the World Heritage Committee it would spend $716 million between 2015 and 2020 on the reef when evaluating whether it should be placed on the international endangered list, but was way behind.

Whish-Wilson: “Could you tell us what the implications would be for the Government if the reef were classified by the World Heritage Committee as World Heritage in Danger.

Rose: “I think there are implications for the Government and implications for the country. Obviously, it’s a terrible look for the Government with this iconic marine park that they’ve neglected to look after.

“The World Heritage Committee is quite a powerful committee in terms of the publicity it can generate in instructing or letting people know that it has been listed as in danger.

“There are ramifications for the country with that listing, as well, in terms of tourism and our role as a player in the international diplomacy. It’s a very big deal.

“So the Government does have that imperative to try and spend the money and show that it’s trying to do something about the reef.”

Whish-Wilson: “To try to head off a World Heritage in Danger listing?”

Rose: “Yes.”

The economist said that even with the one-off grant to be spent progressively, the Government would still be $34 million short of its promise at the end of 2020 when the committee reviewed the endangered listings.

“My understanding is that the environment department and the Government had to do a lot of lobbying around the World Heritage Committee in 2016 to avoid any endangered listing,” Rose said.

“So, if we haven’t met our promise, I’m not sure how fondly the World Heritage Committee will look upon us not being listed as in danger when they meet again in 2020.”

The Senate committee inquiry has provided mountains of ammunition for Labor to attack the coalition when Parliament resumes next week. Labor is demanding the Government withdraw the grant because of the lack of transparency and accountability in the process.

This is likely to get very messy for Turnbull.