Dan Clays has been named UK chief executive of Omnicom Media Group, Britain’s second-biggest media buyer by billings.
Clays, who has been chief executive of OMD UK since 2015, replaces Philippa Brown, who has run the UK division for 12 years and is moving to be global chief executive of PHD.
He will be responsible for his old agency OMD UK and sister businesses including Manning Gottlieb OMD, PHD and Hearts & Science.
Omnicom Media Group UK was ranked Britain's second-biggest media buyer with £1.4bn in billings behind WPP’s Group M in Campaign’s annual School Reports in April.
Leading clients include Disney, John Lewis & Partners, McDonald’s, Sainsbury’s, the UK government and Volkswagen Group, and it employs about 1,900 people.
Clays said of his new role: "It is a fantastic opportunity to build on Philippa’s incredible success and leadership over many years in the role.
"I am excited to take on responsibility across four outstanding and distinctive agencies and also our exceptional specialist services.
"We will continue to embrace bold change to drive the growth of our clients’ business and create more opportunities for our talent across the UK."
Clays, who is 45, spent his early career at Carat and PHD, before switching to independent shop BLM, where he led its digital agency Quantum.
He joined OMD UK as managing director in 2012 and went on to become chief executive three years later.
Clays’ team endured a tough period in 2017 when OMD lost a string of international accounts, but he proved his skills with clients as the UK operation fought back to win new business from Barclays, Betway and Lidl.
OMD UK also became one of the first network agencies to agree to use ISBA's tougher and more transparent media agency framework as part of Barclays' review.
Tim Pearson, chief executive of Manning Gottlieb OMD, will take on Clay’s previous responsibilities in an expanded role as chief executive of OMD Group UK.
Pearson, who will oversee both OMD UK and Manning Gottlieb OMD, will report to Clays.
There are no plans to merge the two agencies.
Cooper said: "We are extremely fortunate to possess outstanding media agencies in the UK that compete very effectively at the highest level and consistently win major awards.
"I’m delighted that we have some of the best talent in the industry and we can therefore confidently promote from within at OMG UK.
"Dan Clays and Tim Pearson are two of the industry’s finest leaders and have each demonstrated that in these transformative times speed, agility and innovation are key to success."
Virtually all of Omnicom Media Group UK's operations are in London, although PHD has an office in Manchester.
Omnicom Media Group faces several key pitches, including Disney’s global media consolidation of its Disney and Fox accounts, in the coming months.