Clay will be working alongside the chief executive, Tess Alps, and the research and strategy director, David Brennan, to develop and drive Thinkbox's strategic and communication activities.
Clay will lead the seven-strong marketing communications team, all of which will report to her, including the head of content and the head of communications. She will be responsible for driving communication activities to agencies and advertisers, including direct marketing and sponsorship campaigns, creating partnerships, managing Thinkbox events and developing the website.
Clay leaves JWT after ten years, during which time she was the deputy managing director and head of client services. She said: "I've enjoyed my time at JWT, but the lure of TV, the Thinkbox role and Tess was irresistible."