In their new roles, both will report to Matthew Wigham, the head of investment at OMD UK Group.
Byron has been at OMD for 13 years and was previously the group investment director. He takes up his new role with immediate effect and will focus on efficiency and campaign execution.
Byron takes over from Chris Amor, who has left the Omnicom agency after 18 years to become the investment director at Omnicom Media Group’s buying shop OPera.
Fox has been appointed the head of implementational planning, a role she formerly held at Manning Gottlieb OMD. Her remit is to strengthen the agency’s cross-media solutions and bring new-to-market opportunities to clients.
At Thinkbox, the commercial TV marketing body, the former head of planning Zoe Fuller is returning from maternity leave to the new role of head of industry programmes. Leila Travis, Total Media’s head of TV, is to become the head of planning.