WPP (WPP.L), the world"s biggest advertising company, launched into open conflict with its founder Martin Sorrell on Thursday, refusing to pay share awards and accusing him of leaking client information to the media. In a twist that pits WPP against the world"s most famous advertising executive, the British firm said a long-term incentive share scheme would lapse after it found the former CEO had leaked confidential details while he was running the firm. The 76-year-old Sorrell, now running fast-growing digital challenger firm S4 Capital (SFOR.L), denounced the move, describing it as petty and motivated by anger at his success. "It’s a bit rich that they’re accusing me of leaks, given their own over the last three years," Sorrell told Reuters. "They’ve had to go back several years to try and find an excuse to deny me what’s mine. I’ve left it to my lawyers to deal with." WPP declined to comment on Sorrell"s response. Sorrell, the most famous advertising boss of his generation, built WPP into the world"s biggest advertising company through a string of major deals over three decades to offer advertising, media buying services, public relations and data analytics to global brands such as Ford, HSBC and Unilever. In the process he became one of Britain"s most high-profile businessman, mingling with politicians and presidents around the world. He left the British firm in 2018 over a complaint about personal misconduct which he has always denied. His new firm has a market value of 3 billion pounds ($4.2 billion) and a large roster of clients. WPP (WPP.L), the world"s biggest advertising company, launched into open conflict with its founder Martin Sorrell on Thursday, refusing to pay share awards and accusing him of leaking client information to the media. In a twist that pits WPP against the world"s most famous advertising executive, the British firm said a long-term incentive share scheme would lapse after it found the former CEO had leaked confidential details while he was running the firm. The 76-year-old Sorrell, now running fast-growing digital challenger firm S4 Capital (SFOR.L), denounced the move, describing it as petty and motivated by anger at his success. "It’s a bit rich that they’re accusing me of leaks, given their own over the last three years," Sorrell told Reuters. "They’ve had to go back several years to try and find an excuse to deny me what’s mine. I’ve left it to my lawyers to deal with." WPP declined to comment on Sorrell"s response. Sorrell, the most famous advertising boss of his generation, built WPP into the world"s biggest advertising company through a string of major deals over three decades to offer advertising, media buying services, public relations and data analytics to global brands such as Ford, HSBC and Unilever. In the process he became one of Britain"s most high-profile businessman, mingling with politicians and presidents around the world. He left the British firm in 2018 over a complaint about personal misconduct which he has always denied. His new firm has a market value of 3 billion pounds ($4.2 billion) and a large roster of clients. WPP, now led by the one-time Sorrell protege Mark Read, said in its annual report that its compensation committee had exercised its discretion to deny giving the former CEO share awards from a 2016 and 2017 scheme. It said the decision was made due to "Sir Martin Sorrell’s disclosure of confidential information belonging to WPP and certain of its clients to the media during his tenure as a WPP director." WPP published a trading update on Wednesday that showed the goup had returned to organic quarterly growth for the first time since the third quarter of 2019. Sorrell"s S4 reports next Tuesday. ($1 = 0.7169 pounds)