The NSW One Nation senator, Hanson’s long-term friend, had been trying to gain a guarantee she would back his nomination once again for his Senate spot at the next federal election.

But Senator Hanson had refused to give him that commitment, instead choosing to cast a wide net to see if other strong candidates would come forward.

In the month since nominations opened, 13 people keen to fill the spot stepped forward for vetting.

Burston was said to be deeply unhappy, while sources close to Hanson say she had lost confidence in her old friend’s political judgment.

“He’s been planning to be a wrecking ball for a while,” the source says.

Their relationship had grown frosty, with Hanson removing him as party whip and Burston deleting all references of One Nation from his Facebook page last month. But the tensions explosively came to a head this week.

Last Monday morning, Hanson organised a conference call with Burston and Senator Peter Georgiou where she raised the idea of backing down on her support for the Turnbull government’s company tax cuts for companies turning over more than $50 million.

Georgiou agreed while Burston is understood to have said he was happy to hear all sides and discuss it further. By that afternoon, Hanson had firmed in her decision she was no longer going to support the tax cuts.

She rang Georgiou and explained her reasons, and then made a similar phone call to Burston. He was about to go in for a medical procedure and the conference call with him, and her chief of staff James Ashby, is said to have lasted around five minutes.

It is understood he raised no objections during that phone call.

About 10 minutes after the call with Burston, Hanson asked for The Australian journalist Joe Kelly to visit her office for an interview, which would run prominently the next day.

However, after his procedure, Burston sent a text message to Ashby at 8.46pm which read:

“We need to have a face-to-face re the company tax cuts. I am not comfortable reneging on a handshake deal we made. We will loose (sic) our credibility if we walk away from this.”

His change of heart came too late. The pages of The Australian were already on their way to the printers.

The following morning, Hanson asked Burston for a catch-up but he is said to have replied that he was too unwell.

The One Nation leader felt betrayed and mislead when she discovered that he was well enough to meet with Leader of the Government in the Senate Mathias Cormann that same day, and to go to Public bar in the upmarket Canberra suburb of Manuka that evening for drinks with Georgiou.

Hanson turned up at the same pub, and neither party greeted each other, sitting at separate tables.

Hanson also discovered that Burston had dined with Liberal Democrat leader David Leyonhjelm the week before at a well-known pub in Canberra called The Kingo to speak about the possibility of defecting to his party.

Leyonhjelm confirmed to Saturday Extra that Burston had raised the idea of forming a voting bloc with other crossbenchers including former One Nation senator Fraser Anning and Australian Conservative Cory Bernardi.

Those discussions were short-lived.

Leyonhjelm says Burston “did say he had no intention of leaving One Nation, but he also raised various ideas (about a voting bloc)”.

“If you’re talking within the Senate, there’s actually merit in that idea because you need numbers to get anything done,” Leyonhjelm says.

“I had a discussion with Brian after the reports he’d taken One Nation off his Facebook page ... I knew he was unhappy, it’s obviously got worse since then.”

But the relationship between Burston and One Nation was about to deteriorate further.

The Saturday Telegraph has obtained a formal letter Burston sent to his chief of staff Peter Breen, dated May 24, banning him from any work for One Nation, unless he took leave without pay.

“I am concerned about a potential conflict of interest arising from your employment as my chief of staff under Commonwealth employment law, and your position as an office bearer of Pauline Hanson’s One Nation political party in NSW,” Burston wrote.

“As a condition of your ongoing employment, I ask that you refrain from doing any further work for Pauline Hanson’s One Nation, and resign from the roles of Secretary and Party Agent in NSW effective from 30 June 2018.”

On Thursday this week, Burston sent an even more inflammatory legal letter, seeking compensation from Ashby — Hanson’s closest adviser — for allegedly leaking information.

It related to an on-air Sky News discussion, between hosts David Speers and Laura Jayes, where they discussed Burston having a “rectal examination” while the company tax cuts policy was discussed in the party.

The legal letter accused Ashby of leaking the personal detail about his health. “I am writing to you to seek restitution and compensation for the injury to my privacy and reputation caused by your damaging revelations,” Burston wrote in the letter dated May 31.

“In the event that you are unable or unwilling to provide appropriate recompense and an apology within 30 days, then it is my intention to pursue this matter with a formal privacy complaint to the Australian Information Commissioner.”

Indicating the Senator had no intention of remaining in the One Nation party, he had removed the party descriptor from his signature.

It was simply a formality when Hanson officially asked the man who was once one of her closest confidantes to resign yesterday, ending a humiliating saga for the One Nation party.