The company has hired Gina Ramson-Williams, previously HR director at WPP media-buying agency Mindshare, to take the role.
Ramson-Williams effectively replaces HR director Liz Fraser, who left WS in August amid a raft of senior departures (PRWeek, 11 Aug).
Ramson-Williams reports to UK & Ireland CEO Colin Byrne and is working closely with head of learning and development Connie Philips, who joined earlier this year.
She worked at Mindshare for six years. At WS she heads an HR team of five.