Foster has worked for Millward Brown South Africa and Impact Information, the company before it was bought by Millward Brown, for over 20 years.
He is best known for developing AdTrack, the ad testing service provided by Millward Brown in South Africa.
Foster, who was joint deputy managing director, will report directly to the chairman of Millward Brown Erik du Plessis and work alongside deputy managing director Christine Malone.
Du Plessis said: "Charles is a great asset to the company. He has grown tremendously since he started with Impact Information in 1986, and has gained much respect within the industry."
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