As far back as January, Treasury officials said the findings from an evaluation by the Ministry of Business, Innovation and Employment were concerning enough to trigger a rethink of the subsidy scheme. "In my view, the estimates warrant a review of the policy setting to improve value for money," said one official.
Questions sent to Parker this week by the Weekend Herald went unanswered.
Parker initially seemed to be mulling the recommendation, saying in May - following a Weekend Herald investigation - that he was looking at changing the scheme, including capping payouts to limit taxpayer exposure. The ballooning cost of the policy is now resulting in $130m being paid out annually.
But by September Parker had performed an about-face, now saying changes were not needed. "We accept that the subsidies are necessary, and we accept there's a benefit to the country," he said.
Screen veteran John Barnett, who ran South Pacific Pictures for 25 years, was scathing of the officials who questioned the subsidy scheme: "I'd love to see the idiot who wrote it, it's facile."
Barnett said the additional spending brought into the economy by the scheme made it worthwhile, and rubbished suggestions from officials that money - and capital investment and workforce training - might be better allocated elsewhere.
"It's a bit Trumpian to say this money should have gone elsewhere," he said.
The Treasury briefing documents note that the cost of the scheme has been escalating. This year the billionth dollar since 2004 is to be paid out, and another $500 million is expected to be spent over the next four years.
James Cameron's big-budget sequels to Avatar, now filming in Wellington, are expected to trigger payouts in the hundreds of millions, while Sir Peter Jackson's Mortal Engines, opening next month, has claimed $24.5m to date.
Barnett said the subsidy scheme was "well-police and audited" and generated spinoff benefits in tourism, training and national identity.
"Someone at Treasury has an almost jealous view of these people wandering around with their hats back to front, who don't tuck their shirts into their pants, but it has changed the way New Zealanders see themselves," he said. "Treasury can't put a price on that."
The Treasury documents note that claimed tourism boosts from film-making were impossible to measure, but if this was the objective of the policy, it might be better to divert the grant into explicit tourism promotion.
The current iteration of the subsidies, the Screen Production Grant, is an evolution of previous schemes for international film producers that have steadily ratcheted upwards over the past 14 years.
When first introduced they provided cash payments to producers of 12.5 per cent of spending in-country, rising to 15 per cent in 2007, before being increased to a maximum of 25 per cent in 2013.
Treasury officials said the 2013 increase had not seen more film work flow to New Zealand, suggesting the international industry was driven mostly by cost and the country was engaged in a risky international bidding war it was unlikely to win.
"'Bidding wars amongst jurisdictions will occur until only the lowest-cost jurisdictions remain," officials warned.