Whatever Sir Martin says about a smooth transition, the fact that the chairman, Roberto Quarta, is stepping in to run the company shows the ground had not been properly prepared.
He said that he leaves the company in "very good hands", with Read, Scott and the management team at all levels having the knowledge and abilities to take WPP to "even greater heights, as well as capitalise on the geographic and functional opportunities".
In an email to WPP staff on Saturday night seen by Sky News, Sir Martin said it was "in the interest of our clients...and all our other stakeholders...for me to step aside".
He added: "We have weathered hard storms in the past". In addition, Mark Read, chief executive of Wunderman and WPP Digital, and Andrew Scott, a top executive at WPP's European operation, have been appointed chief operating officers. "And our highly talented people have always won through, always", said Sorrell.
Sorrell transformed a tiny wire basket manufacturer he acquired in the eighties into an global giant worth over £20bn, with industry figures saying he will a hard act to follow at a time when the industry is facing major headwinds. His share awards will be pro-rated in line with the plan rules and will vest over the next five years, to the extent Group performance targets are achieved.
A first-generation Jewish immigrant in Britain whose parents came from Kiev, Ukraine, Mr. Sorrell got his big break in advertising when he joined Saatchi & Saatchi in 1975. He worked closely with the brothers Saatchi (Charles and Maurice) and helped fashion its rapid growth, before going solo and acquiring a shopping basket manufacturer Wires & Plastic Products (WPP).
Shares in WPP are expected to fall tomorrow when the markets open.
In 1989, he surprised the advertising world with a hostile $825 million takeover of Ogilvy & Mather, then one of the most influential ad agencies, and continued to snap up global competitors, including Young & Rubicam, a global marketing and communications company.
Along the way as his legend grew - so did the amounts he took as payments for his hard labour which caused heartburn to investors and shareholders. But Sorrell's future with the company has been in peril since earlier this month when the firm started investigating the chief exec for misuse of funds and "personal misconduct".
Sorrell's last few words in his farewell note will not only tug at WPP staff's heartstrings but nearly anyone's.
"I will particularly miss the daily interactions with everyone across the world and want to thank them and their families for all they have done, and will do, for WPP", Sorrell added.