The move frees up European managing director John Spanswick from day-to-day responsibilities.
Stephen Hockaday joins the board to head PFI and facilities management activities and Sergio Casari has responsibility for eight countries, including Spain, Italy and France.
Judy Lowe, of Strategic Consulting, is to become a non-executive director.
The move follows last month's appointment of Larry Atkins as global chief operating officer.