Mr Chamberlain was a founding partner of St James Place and led the adviser firm Succession. He founded Succession in 2009, which has grown to 350 Financial Planners. He was also the founder of the Thinc Group (now Bluefin).
He was also a former development director for Zurich in the UK, moving 5,000 individual advisers into a structured business practice model.
He held various non-executive board positions, and was an adviser to Plymouth University Business School and a TISA board member.
In a statement released this afternoon, the company said: “Succession is sad to announce the sudden death of its founder and Group CEO, Simon Chamberlain, 51, who died earlier today.
“Our thoughts and concerns are with his wife Helen and children Charlotte, Henry and Olivia at this difficult time.
“No further announcements are being made.
“Succession will continue to be led by its experienced management team, headed by Chairman Ray Pierce.”
The cause of death has not been disclosed yet.
Last year in May, he told his local paper The Plymouth Herald that he was planning to retire aged 55.
He was quoted as telling the paper: "I've got a train to catch. My wife and I said that when we reached our 55th birthday we'd go to Paris and catch the first 12'Oclock train out to where ever.
"It might be 2018 or 2020 but it will happen. After that, we'll just see where that train takes us."
Financial Planning Today Editor Kevin O'Donnell said: "I knew Simon for 20 years and always enjoyed his company. He built and expanded many financial advisory and Financial Planning businessess during that period - a true entrepreneur."
"In person, he was dynamic, charming and forthright with a very good sense of humour and the industry is an emptier place without him. Our thoughts are with his family, friends and colleagues."
Succession Group CEO Simon Chamberlain dies suddenly - such sad news. I liked Simon. He was a maverick & a pioneer. https://t.co/u4gnSdPJQ0— Jason Butler (@jbthewealthman) March 17, 2017
@FPTodayNews Deeply sad news. My condolences to his family. One of the good guys.— Campbell Edgar (@CampbellSP2) March 17, 2017