Liam Cahill, a former RTÉ journalist, passed away suddenly at his home in Meath yesterday.
Mr Cahill worked in the national broadcaster for a number of years, first reporting on economics and later as a political correspondent.
He was also a historian, an author, a former Government advisor, and a Labour activist.
His first book, Forgotten Revolution: The Limerick Soviet 1919, was published in 1990 and a follow-up was released in 2019.
From Suir to Jarama, Mossie Quinlan’s Life and Legacy, his most recent book, was published just last year.
Mr Cahill is pre-deceased by his wife Patricia and is deeply regretted by his daughter Susan and son Eoin.
Condolences have flooded in for the writer on social media, with many expressing their shock at his sudden passing.
President Michael D Higgins paid tribute to the Waterford man, saying he made a “wide and varied” contribution to Irish society.
“It included his work, his research, and his writing as a journalist, historian, and as an adviser across political and public affairs,” he said.
“To all of this, he brought a well-informed, humorous and passionate spirit.”
President Higgins said he was due to meet with Mr Cahill again soon to be presented with his most recent book, and is very saddened that now won’t happen.
"To all of his many endeavours he brought, and has left, a particular personal legacy. His work in seeking to bring greater attention to the Limerick Soviet of 1919 reflected a particular interest in the cosmuintir, and the excluded or neglected,” Mr Higgins added.
"He presented a copy of his book on this to me in Áras an Uachtaráin.
“I had the privilege of engaging with Liam many times over the years.
"Indeed, he was due to visit the Áras again in the coming weeks to present me with a copy of his most recent book, From Suir to Jarama, which shed light on the story of his cousin Mossie Quinlan, a volunteer in Spain with the British battalion of the International Brigade.
"It is a great sadness that we will not get the opportunity to have that meeting.
“May I express my deepest sympathies to his daughter Susan, his son Eoin, to all of his wider family, and his many friends across the political spectrum.”
The Ambassador of Ireland to the United States, Daniel Mulhall, said he was very sad to hear of Mr Cahill’s passing.
"He was a few years ahead of me at school,” he wrote.
“I later knew him as an RTÉ journalist, a political adviser, media professional, historian & Gaelic Games enthusiast. Ar dheis Dé go raibh a anam dílis.”
Cathy Halloran, RTÉ’s Mid West correspondent, wrote: “Very shocked to hear this sad news.
“I worked with Liam at RTÉ and he also worked with my late Dad Danno in the newsroom & I always enjoyed his recent social media posts—his writing & long working life a gift & legacy.”
RTÉ’s Martin Kiely said: "My sincere sympathy on the passing of Liam. A man with such knowledge across so many areas.
"He loved politics and of course GAA. Just recently he sent me a very nice comment after a broadcast. A man with the power of words but also with great humanity. May the light of heaven shine on him. RIP.”