Meredith joins Rapier as its planning director and replaces Gill Davies who left the agency earlier this year.
Rapier has a team of 15 strategists and communications planners. Meredith will work jointly alongside Jonathan Bean, who was appointed from the consultancy company Bain to head its team of strategists.
Meredith has headed Proximity's planning department since August 2000.
Before joining Proximity she was a marketer at Marks & Spencer Financial Services. During her time at Proximity she also had a personal involvement in the running of its Sainsbury's account. Shona Forster, Proximity's executive planning director, assumes day-to-day responsibility for its planning department.
Rapier has attempted to build a planning resource that includes a range of disciplines. Earlier this year, it strengthened its team by hiring from ad agencies, media agencies and management consultancies. Its recent work has included Npower's brand positioning and through-the-line work for Axa.