Marshall (pictured) is a high profile industry figure and head of the IPA media futures group, in which role he has led initiatives such as the IPA Touchpoints system.
He now plans to establish his own media consultancy business with SMG as his founding client.
He will maintain a relationship with the media agency until spring next year and his responsibilities will be spread among SMG’s senior team over the next six months..,
Marshall has worked at Publicis-owned Starcom for more than 20 years and was deeply involved in the creation of the SMG structure. Positions he has held include chief executive of MediaVest.