Chadlington, who is 72, told PRWeek yesterday that he had made the decision more than a year ago to step down after 14 years leading the group, which he founded having sold his previous agency Shandwick to Interpublic before the turn of the century.
He was saluted as "one of the greats" of the PR industry by former colleague Jonathan Clare, who ran Citigate for more than 20 years and was working there when it came under Huntsworth's control in 2005.
The lasting impression of Chadlington is that he is "extraordinarily well connected", according to Clare, now executive chairman of Huntsworth rival Newgate Communications.
"Anybody who is anybody in the corporate world will have come across him," he said.
Clare believes that the big challenge facing Huntsworth following Chadlington’s departure wil be replacing him and still keeping the group together.
Clare pointed to the lack of internal candidates capable of taking over from Chadlington, who has said he will remain in place while the group searches for his replacement. Clare said: "If you were advising a client you would have a succession plan in place, so that will be a bit of a challenge – to do that in a semi-public environment."
He added: "[Chadlington] built Huntsworth by acquisition but the group is disconnected and has few synergies. The big challenge now is to keep it together."
Huntsworth's agency line-up includes multidisciplinary global offering Grayling, Huntsworth Health, international financial PR brand Citigate and UK consumer shop The Red Consultancy.
PRWeek approached several current Huntsworth employees for comment, but none were prepared to speak on record.
One former employee claimed that the group's shareholders may have been unhappy about the style of management and the company's performance. The 27 per cent rise in Huntsworth's share price between the end of Friday and yesterday's close suggests that investors are not mourning Chadlington's departure.
However, he has many supporters within the PR industry, including PRCA director-general Francis Ingham, who called him a "titan".
Ingham said Chadlington had a "360-degree vision for a modern communications business that has been much imitated but rarely matched".
Bell Pottinger founder Lord Bell commented that this week marked the 50th year of his close friend's career, adding that while he was not surprised by the news he was sad to see Chadlington leave.
Bell said: "He built Shandwick into the biggest company in the world and he was in the process of doing that with Huntsworth, and he’s decided that he had been there long enough and would rather work part-time."