Sorrell's 1985 investment in Wire & Plastic Products and string of acquisitions of advertising companies that followed effectively founded WPP, making him an executive seen by some as irreplaceable for his direct access to clients and active hand on a sprawling network of agencies.
The question now for his successor, WPP's investors and its tens of thousands of clients is whether the £15bn group can survive the departure of its founder and the dramatic changes the internet is bringing to the traditional world of advertising. As per the official press release issued on the company site, "the previously announced investigation into an allegation of misconduct against Sorrell has concluded". These are methods his successor can not hope to be allowed to employ.
The news is likely to impact the share price of WPP as well as have wider implications for the advertising industry, including WPP AUNZ.
Roberto Quarta, the company's chairman, will now lead the organization in the interim. "He wasn't widely liked but he was universally admired".
Mark Read, chief executive of Wunderman and WPP Digital, and Andrew Scott, WPP corporate development director and chief operating officer, WPP Europe, have been appointed as joint chief operating officers of WPP.
"Obviously I am sad to leave WPP after 33 years", Sorrell says in a statement.
WPP PR Companies operating in Australia include Ogilvy PR, Burson Marsteller, Hill & Knowlton, PPR, Pulse and several conflict agencies. I reject the allegation unreservedly but recognize that the company has to investigate it.
Sorrell, who will continue to be available to the board with his valued guidance signed off saying, "As a Founder, I can say that WPP is not just a matter of life or death, it was, is and will be more important than that". He denied the allegations but in a letter to WPP staff published late on Saturday he said the "current disruption" was "putting too much unnecessary pressure on the business". "There is no other Sir Martin Sorrell in the world".
He owns shares in WPP worth more than £200m, while his annual remuneration packages - he earned £70m two years ago - have made him a target for critics of lavish boardroom pay.