WPP is facing an investor backlash over the terms of Sir Martin Sorrell’s departure which puts him in line for a £20m windfall. One investor told The Telegraph that they were “furious” the business was allowing the advertising tycoon to pocket up to £20m in share bonus awards over the next five years following an allegation of personal misconduct.

Sir Martin has denied any wrongdoing.

“We are going to be looking at it all – why he is allowed to leave with such [generous terms] and the lack of a non-compete agreement,” the shareholder said.

Pressure is expected to mount on the company to release details of the alleged offence. Sources say only lawyers on both sides and WPP’s 11-person board have been made privy to the details, leaving the City in the dark about the investigation as its annual general meeting looms in June.