As first revealed on PRWeek.com last week, Ward is leaving to spend more time with her family. She is negotiating her departure date, but is likely to be with the agency until the end of the year as she hands over major accounts such as Cadbury, Coca-Cola and Mastercard.
Ward, a consumer PR specialist with 20 years' experience, has been with WS - whose UK and Ireland CEO is Colin Byrne - for five years, having joined from Porter Novelli, where she was business development director. She sits on the European board and reports to Tim Sutton, chairman, Europe.
Meanwhile, former Sun editor Yelland is quitting as senior vice-chairman after two years to become a partner at City PR rival Brunswick. Yelland is on a three-month notice period, making him free to join Brunswick in October.
The exit terminates WS's relationship with Tesco with immediate effect. Yelland has counselled the supermarket on media strategy since the middle of last year amid growing concerns over its dominance. He also worked on the agency's accounts with Coke and Multiplex, the Australian developer of the troubled Wembley Stadium.
Yelland has been a friend of Brunswick founder Alan Parker since his days on The Sun's City desk in the 1980s.