Merger to create world's biggest ad firm

France's Publicis and US firm Omnicom announce a merger to create the world's biggest advertising company, worth £35bn. The plans leave some analysts confused about the direction of the new company, whose clients would include Coca Cola and Pepsi, as well as Microsoft and Google. We speak to Sir Martin Sorrell, whose firm WPP will be ousted from top spot when the deal is finalised.