That Tuesday evening, Treasury boss Gabriel Makhlouf and Finance Minister Grant Robertson released statements saying that the Treasury had been systematically hacked , and that the police had been called in.
Ardern has given different timelines of when the GCSB information came to the Beehive, but Parker today clarified matters during Question Time.
Watch: Question 1 - Hon Simon Bridges to the Acting Minister responsible for the GCSB
Parker, who is acting GCSB Minister while Andrew Little is overseas, said the GCSB contacted Little's office at 8.43pm on Tuesday May 28.
That was about 40 minutes after Makhlouf publicly said that his department had been hacked, and about 30 minutes after Robertson echoed Makhlouf's description and linked it to the Budget material the National Party had obtained.
Ardern told the House that Little did not answer the 8.43pm call because he was in a meeting, but the GCSB also contacted the head of the Department of Prime Minister and Cabinet at about the same time, and she was notified soon afterwards.
Parker said that Little didn't actually speak to the GCSB until 9.43pm, and he then immediately tried to call Robertson. After not receiving an answer, Little contacted Ardern's office, and he eventually sent Robertson a text message at 10.25pm that night.
Parker rejected that there had been any delay in passing on the GCSB information.
"There wasn't a delay of hours. Immediately upon the conversation between Minister Little and GCSB, he put a call into Minister Robertson," he told the House.
"Minister Robertson was not available and did not pick up, so Minister Little immediately contacted the Prime Minister's office and spoke to the Prime Minister's deputy chief of staff."
Ardern said during Question Time that the GCSB told Ministers that what had happened to the Treasury was "unauthorised access".
She defended the original description of what happened as systematic hacking, saying "that was the information that we had" at the time.
Bridges said that Ministers had allowed a "fundamental mistruth" to permeate the following day by not revealing the GCSB advice, but Ardern rejected that.
She said Ministers changed their language according to the GCSB advice, and they still did not know whether anything illegal had happened and wanted to let the police do their job.
She said she was told about police advice that nothing illegal had happened on the following evening on May 29, and the Treasury released a statement revealing that police advice the following morning, May 30, at 5am.
Bridges has called for Deputy Prime Minister Winston Peters to apologise for saying that the National Party had acted illegally, but Peters again stood by his previous comments today.
Peters added that he believed National had engaged in "hacking" and, during Question Time, he referred to a section of the Crimes Act about intentionally accessing a computer system without authorisation.
The State Services Commission is conducting an investigation into whether Makhlouf misled the Government.
It is also doing a separate inquiry into how sensitive information on the Treasury's website wasn't secure.
Today the commission announced that Murray Jack would head that inquiry, and it would look at what happened, why it happened, the lessons learned, and the actions the Treasury needed to take to prevent it happening again.
Jack is a professional director, Chair of Chartered Accountants Australia and New Zealand and a former member of the board of the Financial Markets Authority. He was previously chairman and chief executive of Deloitte NZ.
Timeline
Tuesday, May 28
• 10:01am: In a press release, National publishes what it claims to be details of the 2019 Budget
• 11:30am: Finance Minister Grant Robertson confirms some of the details in National's release are from Budget 2019
• Afternoon: National releases more Budget details
• 2pm: National says its method of accessing the Budget information on the Treasury website is closed down.
• Before 6pm: The Treasury asks the cybersecurity unit of the Government Communications Security Bureau about how confidential information on its website was accessed. The GCSB says the Treasury's computer network was not compromised, and the matter should be referred to the police, given that it's not what the GCSB normally responds to
• 6pm: Treasury Secretary Gabriel Makhlouf refers the matter to the police
• 7pm to 7:15pm: Makhlouf meets Robertson in his Beehive office and tells him that he has called in the police. Robertson says that Makhlouf described it as 2000 attempts to "hack" the system. Meeting is later attended by Jacinda Ardern's chief press secretary Andrew Campbell and deputy chief of staff Raj Nahna.
• 7:20pm: Robertson calls Ardern to inform her of latest developments
• 8:02pm: The Treasury issues a press release saying it has "sufficient evidence" that it had been "deliberately and systematically hacked". It cites the GCSB advice in saying it has been referred to the police.
• 8:19pm: Robertson issues a press release, asking National not to release any further information because "the material is a result of a systematic hack".
• 8:43pm: The GCSB contacts the office of GCSB Minister Andrew Little to say it doesn't believe any systematic hacking took place. Little is in a meeting. The GCSB contacts the Department of Prime Minister and Cabinet to pass on its concerns, and Ardern is told soon afterwards.
• 9:43pm: Little speaks with the GCSB and then tries to call Robertson. The call is not answered.
• 9.52pm: Little contacts Nahna in Ardern's office to pass on the GCSB's concerns.
• 10.25pm: Little texts Robertson about the GCSB's concerns.
Wednesday May 29
• 7:04am: Makhlouf tells media there had been 2000 attempts to access the Treasury's system in 48 hours
• 9am: Simon Bridges strongly denies the information released by National came into its possession unlawfully, but refuses to say how it was obtained. Says it is a "lie" to say the Treasury was hacked.
• Afternoon: Deputy Prime Minister Winston Peters says National has acted illegally.
• About 6pm: Robertson and Ardern are told that police have advised the Treasury that nothing illegal appears to have happened, and a statement will be released in the morning.
Thursday May 30
• Thursday, 5am: Treasury releases police advice. State Services Commission, at Makhlouf's invitation, launches inquiry into how the Treasury's Budget information was accessed.
• 8:45am: Simon Bridges fronts a press conference where he outlines how National used a simple search function to get the info. He says the Treasury has "sat on a lie" and calls for Makhlouf and Robertson to resign for smearing the National Party, and for Peters to apologise.
• Afternoon: Peters stands by his earlier comments and won't apologise. Says lawyers, such as himself, would know what constitutes illegal activity better than the police.
Friday May 31
Paula Bennett writes to SSC, asking for it to investigate Makhlouf and Robertson and whether they have acted appropriately.
Tuesday June 4
• 3pm: Ardern says she expects the commission to look into the quality of advice that Treasury provided to ministers.
• 4:30pm: State Services Commissioner Peter Hughes announces new investigation into whether Makhlouf misled the Government, to be conducted by Deputy State Services Commissioner John Ombler.
Friday June 7
• Herald reveals that the GCSB urgently contacted the Beehive to object to the language being used to describe what happened as "systematic hacking". Robertson says he did not have that information when he released his statement about hacking on May 28.
Monday June 10
• Ardern says that no Ministers learned about the GCSB advice until after the statements about hacking had been released on May 28. National says that Ministers still spent 33 hours "sitting on a lie" and should have released the GCSB advice as soon as they were told about it. Ardern says it was appropriate not to as police were looking into the incident at the time, and a full picture of what had happened did not emerge until later.
Tuesday June 11
• Acting GCSB Minister David Parker, during Question Time, releases the timeline of the GCSB efforts to warn the Beehive about using the term "hacking".