CANNES, France (Reuters) - WPP WPP.L founder Martin Sorrell rounded on the board of the advertising giant he founded on Thursday in his first major public appearance since quitting as chief executive in April.

Sir Martin Sorrell talks during a session in a pub as part of the Cannes Lions International Festival of Creativity, in Cannes, France, June 21, 2018. REUTERS/Eric Gaillard

Sorrell, 73, has denied an allegation of personal misconduct which led to his departure from the world’s biggest advertising company. Neither Sorrell nor the company have given any details about the nature of the complaint.

“The most damaging thing that happened during the course of those events... was the leak over the Easter weekend at the very top of the company, and which to my knowledge there has been no investigation whatsoever,” Sorrell told a packed event in Cannes organized by The Drum publisher.

His rapid exit followed decades of success at WPP which brought great wealth for investors including Sorrell, who earned around 200 million pounds in the last five years alone due to a performance-linked bonus scheme.

Sorrell said he had asked WPP to conduct an investigation into how the allegation had leaked to the Wall Street Journal.

“There has been no investigation to my knowledge of how, why and what the leak consisted of and I think that is a fundamental flaw,” Sorrell said in Cannes, adding that he had requested one.

A spokesman for the company declined to give any further details but said:”WPP takes confidentiality very seriously and is acting appropriately.”

Sorrell added that while WPP says it treats all of its 200,000 employees equally, he did not think this was the case.

“I would disagree violently with that premise, not all employees have been treated equally,” he said.

The departure of the world’s most famous advertising executive prompted speculation as to why he left, including a Financial Times report that he could be aggressive towards staff. Sorrell described the allegations as “scurrilous and salacious”.

“Am I the easiest person in the world to get along with, you know very well that sometimes I can be difficult, but I would always say difficult with justification,” he said, looking relatively relaxed, in a t-shirt and jacket.

“If it is a fault to demand or expect superior performance or for things to go well, mea culpa.”

POTENT COMBINATION

Mark Read and Andrew Scott were appointed to run WPP in the interim after Sorrell quit, with Read focused on running the agency business, while Scott handles its finances.

Sorrell, a 2 percent shareholder in WPP, said the chairman had said he wanted to maintain stability, which he took as a signal that it would appoint an insider. Sorrell said he would back the two men to become joint CEOs if this was the case.

“I’m not saying two individuals because nobody could replace me individually, but those two individuals have complementary skills,” he told ad executives and journalists who had flocked to a small Irish pub on the Cannes waterfront to hear him.

“One on their own would not be sufficient in my view but two together can be a very powerful and potent combination.”

WPP has had to defend its handling of the departure after it emerged that Sorrell had left with share awards worth potentially 20 million pounds and without a non-compete clause.

He has since set up a new venture, S4 Capital with a pool of 150 million pounds from outside investors and acquired a listed shell company, repeating his formula from the 1980s when he used a then little-known firm called Wire and Plastics Products to buy some of the biggest ad agencies in the world.

Sorrell said he expected to work for the next seven years and then assess whether he wants to go on with a new cycle.

And outlining his position in the rapidly changing industry and what he wanted to achieve, he likened his new venture to a peanut. He noted that some people are allergic to them.