Mayfield starts work at the 30-strong Chime agency on 3 January. He joins an executive management team of six under MD Simon Jones and will not have existing clients assigned to him.
He will instead contribute to new-business pitches and advise on the running of the agency, said Jones.
The appointment of someone with experience of running a similarly sized agency signals Harvard’s intention to aggressively chase growth, Jones added.
Midnight CEO Caraline Brown, who this year bought the agency back for £310,000 after selling it two years ago to the BV Group for £3.5m, said it was not yet decided if Mayfield will be replaced.