Marshall, the enfant terrible of New Zealand journalism, had struck again.
Marshall, 27, has been making a habit of infuriating powerful figures ever since he began tailing Mike Hosking in search of a paparazzi payday a decade ago.
But once again, there are questions over the ethics of how Marshall managed to break such a big scoop.
It has been scrutinised by media commentators across the ditch: Alan Jones insists that there were Chatham House rules in place which prevented the naming of speakers.
Marshall says there was no mention of Chatham House rules at the meeting and no one asked whether there were journalists present.
And although Marshall may have been guilty of a little journalistic subterfuge, without the audio evidence he could never have proved that Jones said what he undoubtedly did.
"I feel like I'm on solid ground with this story which was managed ethically from the beginning," Marshall tells the Herald on Sunday over a coffee just up the road from News Limited's Holt St headquarters in Sydney's Surry Hills.
"This wasn't just me out randomly one night with a tape recorder on the streets of Sydney trying to stitch up one of our biggest stars," he says.
"This was a well-managed investigation which wasn't about Alan Jones - it was a story on politics - and I think the ethics sit well with me."
The fallout from the piece continues. The august Sydney Morning Herald, whose owners Fairfax are fierce rivals of the Sunday Telegraph's owners News Ltd, wrote a piece about Marshall, raking over his past in New Zealand.
Marshall, with the backing of his newspaper's crack legal team, has launched his own legal action against the Sydney Morning Herald, citing defamation.
The irony will not be lost on many in New Zealand who feel aggrieved at the way Marshall went about uncovering his many scoops.
The list of those who have accused Marshall of deceit in obtaining his stories is lengthy, from Amanda Hotchin to former "leaky mayor" turned New Zealand First MP Andrew Williams.
Marshall, defiant as ever, flatly denies Amanda Hotchin's claims that he concocted a quote after doorstepping the socialite on holiday in Hawaii.
"Never have I had a Press Council complaint upheld or a defamation proceeding filed with any court."
He has been making headlines ever since he was 15. He appeared on the cover of Metro magazine while still a teenager, and his comments from interviews conducted at the time were oozing youthful arrogance.
So has the move to Sydney finally forced Marshall to grow up?
These days Marshall sports Clark Kent lookalike glasses, and is a dapper follower of fashion.
He may not be Superman but admits he is a man in a hurry.
"I'm not someone who likes to wait. I hate queues or anything that takes longer than 10 minutes."
He is happy to be recorded, yet in the circumstances he could hardly say no. A bystander recognises him from a recent television appearance.
His critics - and he has many on both sides of the Tasman - may beg to differ, but his unexpected scoop has certainly boosted his professional profile and advanced his career.
"I expected to come over here and be anonymous for several years but it's happened quicker than I expected," he remarks.
It is hard to believe that it was only a year ago that he left the Sunday Star-Times, bought a one-way plane ticket for $90 and, with no job offer, headed to Sydney to seek his fame and fortune.
To save money he stayed with friends, including another exile Charlotte Dawson, for the next few months, while pounding the streets and hitting the phone in search of employment at television current affairs shows.
It was bad timing.
With hundreds being laid off in Sydney's media industry, he made little headway.
Marshall had to act fast or starve.
"Unlike New Zealand, there were no lawyers or crooked cops calling me with stories so I had to quickly think how I was going to get myself bylines," he recalls.
He found the answer in so-called concept journalism - dreaming up ideas rather than stories.
He decided to attend a training course for charity workers, which led to the exposure of some dubious fundraising practices.
The Telegraph offered him a few days work a week and within a few months he had drummed up a series of exclusive stories in the Sunday Telegraph, Australia's biggest-selling paper, with a circulation of more than 600,000.
The story goes that when he went for a job at the Sunday Telegraph, an editor dumped a stack of paper charting Marshall's indiscretions on his desk and effectively said, "we know all about your past, but we don't really care".
The scoops kept coming, including a story about former Olympic swimmer Grant Hackett's "heavy reliance" on the sleeping pill Stilnox, a claim which ultimately led to the Australian Olympic Committee banning the powerful drug.
The story, on which he worked closely with Sunday Telegraph editor Neil Breen, won them Splash of the Year at the prestigious Kennedy Awards in August.
Marshall has since taken up the post of investigation specialist across the entire News Limited newspaper group, not just the Sunday Telegraph, with freedom to work from any of the group's offices across the continent.
Breen describes him as "a hell of a journo".
"When we hired Jonathan earlier in the year I said to my deputy: 'this bloke will either get me sacked or win us a Walkley Award'. It looks as though the latter might turn out true," Breen recalls.
"To have made such a mark in Australia inside one year is an amazing achievement." Breen admits Marshall will "do things others won't".
If that is the New Zealander's secret weapon, it also means he has to be kept on a "tight leash", a senior News Ltd source admits.
"He's very high maintenance but he takes direction and delivers, has a real desire to succeed and you can't argue with that."
Marshall, who has now found a home in Sydney's upmarket eastern suburbs, takes criticism on the chin.
"I don't mind people dishing the dirt on me if I'm happy to dish it myself, but it's got to be factual," he points out, a reference to a story in the Sydney Morning Herald about his earlier career in New Zealand and which is now the subject of a defamation suit.
But it was a claim that he was videotaped smoking pot and was the subject of a drug bust in 2003 which really raised his ire.
"It never happened," he insists.
"I've had no drug conviction in Australia, New Zealand or anywhere else in the world and I've never been interested in marijuana."
In 2004, former teacher David Arthur, 48, was convicted of supplying methamphetamine to four people including Marshall.
Not that he doesn't have a reputation for going to ethical extremities in search of a "yarn".
He once donned a hard hat and got into New Zealand Rugby World Cup venues to demonstrate they were vulnerable to terrorist attack.
On another occasion he carried a false knife and gun on to a plane.
But he admits New Zealand became too "vanilla" for him.
"The best decision I've ever made was to move to Sydney," he confides. "I felt like I was trying a whole set of keys and when I walked into Holt St (News Ltd's HQ), I knew I was home."
He is always on the clock, coy about his private life, and has few outside interests apart from cooking. He's bought a slow cooker, which he uses to cook up lamb shanks and chicken stock in his apartment.
Yet although he seemingly has the Australian media world at his feet, some in the industry believe Marshall would struggle to get a job in the industry back in New Zealand.
Marshall puts this down to "differing ideologies" between the two countries. "With some of the community newspaper-minded folk running the show in Auckland, I think coming home would be a very silly idea indeed."
Maverick Jonathan Marshall
At age 11: Diagnosed with attention deficit disorder.
14: First media job, as a DJ on Planet FM - Auckland's access community radio station.
15: Gets a job as a producer and newsreader at Newstalk ZB, aged 15.
17: Requests his personal file from Rangitoto College after leaving school.
18: Starts NZTabloid.com website with former partner David Herkt, makes the cover of Metro magazine.
18: Fired by Livingstone Productions, makers of Queer Nation, over taking paparazzi shots of Mike Hosking.
18: His former teacher David Arthur is convicted of supplying drugs to four students, including Marshall.
22: Studies journalism at Wintec.
23: Works at Herald on Sunday.
23-26: Works for Fairfax NZ.
2010: Accused of making up a quote by Amanda Hotchin, something Marshall emphatically denies.
January 2012: Moves to Australia and finds work with the Sunday Telegraph.
August 2012: Wins the outstanding Splash award for revelations that swimmer Grant Hackett used and abused the sleeping pill Stilnox.
2012: Takes legal action against Fairfax Media for a profile piece in the Sydney Morning Herald.
