FILE PHOTO: Martin Sorrell, chairman and chief executive officer of WPP, the world's largest advertising company, speaks at the Confederation of British Industry's (CBI) annual conference in London, Britain November 21, 2016. REUTERS/Stefan Wermuth/File Photo

LONDON (Reuters) - WPP WPP.L Chief Executive Martin Sorrell is expected to attend a long-planned board meeting next Tuesday despite an ongoing investigation into an allegation of misconduct that was ordered by the directors, a person familiar with his plans said.

WPP stunned the industry last week when it said it had appointed lawyers to investigate alleged misconduct by Sorrell, the founder of the company who built a two-man outfit into the world’s biggest advertising group with 200,000 employees.

Sorrell, 73, has said the allegation regards the misuse of public funds and that he denies them unreservedly.

One person familiar with the process said the investigation was unlikely to be resolved before the end of next week. A second person familiar with Sorrell’s plans said he was expected to attend the meeting because he has continued to work as normal throughout the investigation.

Both spoke on the condition of anonymity due to the sensitivity of the situation. The board meeting has been scheduled in the diary for many months.

The longest-serving CEO on the FTSE 100 blue chip index, Sorrell built WPP into the world’s biggest advertising group by three decades of relentless dealmaking and is one of the most high profile, and best paid, executives in Britain.

The company is now present in 112 countries and provides services to clients including Ford, Unilever, Vodafone and P&G through creative agencies such as J. Walter Thompson and Ogilvy & Mather, and research groups and media buyers.