In the newly created role, Blackett (pictured) will focus on WPP’s strategy of horizontality – ensuring the group presents a simplified offer to clients. She will also identify potential acquisition opportunities and support diverse recruitment for the group.

Blackett held the position of UK chief executive for MediaCom from 2011 to 2015, after which she was promoted to chair. She received an OBE for services to media and communications in 2014, and was the first business woman to be named the most influential black person in Britain.

The UK market represents approximately $3bn in revenue for WPP, according to the company.

Commenting in an internal company memo, WPP chief executive Sir Martin Sorrell said: “Not only has [Blackett] been central to the success of MediaCom, she has also been a tireless champion of diversity in our business, in the wider sector and in public life in general.”

Meanwhile, WPP’s media investment arm, GroupM, announced the appointment of Nick Theakstone to the new role of global chief investment officer. Theakstone was previously chief executive at GroupM.

Based in London and New York and reporting to the group’s global chief executive Kelly Clark, he will be responsible for overseeing the company’s global media investments, trading activities and commercial partnerships.

Tom George will succeed Theakstone as UK chief executive. Johan Boserup continues as global head of trading, reporting to Theakstone.