Lowden's departure was announced earlier today. He was appointed chief executive of TNS in January 2006, having joined the company in February 1999 as finance director before being promoted to chief operating officer in 2003 with responsibility for the group's regional operations.
Prior to joining TNS, Lowden was senior vice-president and chief financial officer, initially of Nielsen International and then of AC Nielsen.
WPP took control of TNS on Wednesday when its £1.1bn takeover offer was declared wholly unconditional with acceptances representing 95.5% of TNS shares, six months after its interest became known.
Ros, managing director of global clients and sectors at TNS, has been promoted to CEO of TNS Custom reporting directly to Eric Salama, CEO of the Kantar Group, WPP's insight division.
The new TNS Custom board will initially consist of Ros and three regional CEOs, Judith Passingham (Europe), Jamie Hall (Asia and Latin America) and David Kieselstein (North America), whose responsibilities remain unchanged.
The Kantar Group has also confirmed the continued positions of the TNS senior management team: Josep Montserrat as CEO of Worldpanel, Jean-Michel Portier as CEO of TNS Media, and Elaine Riddell as CEO of TNS Healthcare. They will all report to Salama.
As part of the integration process, the Kantar Group has established an integration team which will be led by Mike Gettle, previously chief financial officer of Millward Brown.
Salama said: "It is a challenging time for our clients. It is important to have the right management in place to provide excellent on-going service to them and to ensure that TNS continues to flourish.
"We have long admired the quality of the people at TNS and one of our key rationales behind the decision to acquire the business was the talent. Pedro Ros has been a key part of the success of the company and with the other senior management remaining in place at TNS."
Ros joined TNS 20 years ago and has been managing director of global clients and sectors since January 2006, having previously worked across various areas of business around the world.
He was chairman of Latinpanel from 1999 to 2006 and most recently, was responsible for defining and implementing a strategy to service TNS' major global clients.
This article was first published on brandrepublic.com