David Barnett was at the forefront of Australia's political journalism for decades and later became press secretary to prime minister Malcolm Fraser.

Mr Barnett, the husband of former Goulburn MP Pru Goward, died on Saturday aged 90. He passed away in Canberra's Calvary Hospital, following illness.

His journalism career began in 1949 as a copy boy on the Sydney Sun, before spending 13 years overseas starting in London's Fleet Street.

He later spearheaded the first official Canberra bureau of Australian Associated Press more than 50 years ago.

Mr Barnett became the national newswire's first bureau chief in 1971 overseeing two journalists in what's now called Old Parliament House.

He was just in time to report on one of the most seismic shifts in Australian politics - the 1972 election of Labor prime minister Gough Whitlam.

Mr Barnett later served as press secretary to Malcolm Fraser for seven years from 1975, including during the political upheaval that lead to Mr Whitlam's dismissal and Mr Fraser's elevation from opposition leader to prime minister.

Former Liberal prime minister John Howard, who was a member of the Fraser government, said Mr Barnett, who wrote his 1997 biography, was an invaluable adviser to Mr Fraser.

He was a very effective press adviser and a highly significant national media figure, he said.

"I counted him as a good friend."

In a 2010 book published to mark AAP's 75th anniversary, Mr Barnett tells the story of being assigned in 1971 to cover the visit of an ALP mission to China, which included the then-opposition leader Mr Whitlam, with other journalists from News Ltd and the ABC.

"We were taken to the Great Hall of the People, which had been arranged in a horseshoe," he wrote in On The Wire - The Story of Australian Associated Press.

"Whitlam and [then-Chinese premier Chou En-Lai] were to sit at the apex, with chairs reserved for the ALP members.

"I took a shorthand note of every word between the two leaders over what seemed like a couple of hours".

After it was over, Mr Barnett set up in the all-night telegraph office in the Peking Hotel and began writing his story on his portable typewriter.

"My colleagues went to their room. Every time the lift clanked into operation, I would type 'mtc' - more to come - pull the page from my tiny portable Olivetti and hand it to the operators, thus effectively jamming the lines.

"The AAP story swamped the papers and also ran on the Reuter wires."

Soon after, Mr Barnett was approached by a Chinese minder and got a scoop on the first exchange of recognition negotiations between China and Labor.

"If the Chinese could use me to get a message across, then I could send a message on behalf of my country," he wrote.

Former Goulburn Mulwaree mayor Geoff Kettle told the Yass Tribune he first met Mr Barnett when he was working as press secretary to Mr Fraser in the early 1980s. Mr Kettle was employed at The Lodge at the time.

"I admired him then and I've done so ever since," he said.

"David was a unique character and had a great gift for communicating with people. He had a smart wit which he held right up until I last saw him in May."

Mr Kettle said his friend was a total professional, as reflected during his time at AAP and Reuters.

"He was just a bastion of the media and politics and had an intimate understanding of both sides of politics," Mr Kettle said.

Mr Barnett shared stories about sitting in the same room as Mr Whitlam and then Chinese premier Chou En-Lai in 1971, covering an ALP-led delegation to Beijing for AAP.

He also later enjoyed relating conversations he'd had with former prime ministers.

"He was a bloke who could relate to everybody and he never saw himself as being better than anyone else," Mr Kettle said.

"I think that's what gave him his success in the media. David had a great humility, great understanding and great human relations but he was ever the statesman."

He was also a confidante to Ms Goward after her election as Goulburn MP in 2007 and throughout her ministerial roles in the Berejiklian government.

Mr Barnett lived part of his time in Goulburn but the majority on the couple's Yass district property. He continued to write a regular political column for the Yass Tribune and maintained an avid interest in politics. More recently, he shifted into aged care in Canberra.

Ms Goward retired from political life in 2019, saying she could no longer balance her duties and her husband's health needs.

"The most important thing is to be with David and to look after him," she said at the time.

Current Goulburn MP Wendy Tuckerman said she was sad to hear of Mr Barnett's passing.

"David was an integral member of the Yass Liberal branch and a wonderful support during my election campaign. His wealth of experience and knowledge but more importantly his support was so appreciated," she said.

"He will be sadly missed and I pass on my condolences to Pru and family."

Mr Barnett is survived by Ms Goward and daughters Susan and Alice. He was also step-father to Penny Fischer and Tziporah Malkah, Ms Goward's daughters from a previous marriage.