Sir Martin Sorrell - Founder, WPP

Stephen Sackur presents a special edition of Hardtalk from Cannes, which is currently hosting the world's advertising industry. Thanks to the internet, advertising and marketing now have the ability to reach deep into the fabric of our lives. No one has exploited this better than today's guest - Sir Martin Sorrell, the founder and CEO of the giant advertising conglomerate WPP. The ad industry is hugely powerful, but is it responsible?