Guy Phillipson took over as CEO of Internet Advertising Bureau (IAB) in January 2005. Following his 100 day review, the IAB was restructured and repositioned as a valuable resource for marketers to help them make the most of all online advertising disciplines, from search & display to social networks and mobile.

During his first year, online advertising revenues overtook radio, consumer magazines and then outdoor to become a truly mainstream medium. In October Guy Phillipson hosted the IAB annual conference, Engage 2005, which included keynote speeches from Sir Martin Sorrell, Lord Puttnam and Bill Gates, who famously pronounced, "the future of advertising is the internet".  In March 2006, Revolution magazine named Guy Phillipson as Digital Business person of the year.

By the end of 2008 online ad revenue reached a heady £3.3bn and the internet's share of total UK media spend hit 20% - the highest share anywhere in the world.

Before the IAB, Guy was Head of Advertising at Vodafone UK and gained considerable marketing experience at The Marketing Store, Barclays Bank and The Granada Group.