'Keep it simple' - business appeals to 'in' campaign on Brexit

By Elizabeth Piper DAVOS, Switzerland - "Keep it simple, visual and factual" - that is the advice of the most powerful man in advertising to Britain's campaign to stay in the European Union, saying it must focus on the benefits to trade, investment and jobs to win the debate. A second-generation immigrant, Martin Sorrell, who has built the world's biggest advertising group WPP (WPP.L) over 30 years, is passionate about staying in the EU and does not rule out personally contributing to the 'in' c