Emma Walmsley will be one of just seven female bosses in the country's top 100 companies when she takes the helm of GSK next year. The pharmaceutical giant is worth £80bn, making it the most valuable company with a woman CEO. But how did Emma Walmsley get to where she is today? Mark Coles looks back over her school days and her rise up the corporate career ladder at L'Oreal. We hear from her father, retired vice admiral Sir Robert Walmsley, her school friend and her business associate Sir Martin Sorrell, CEO of advertising firm WPP. Who is Emma Walmsley and what impact will she have on one of Britain's biggest companies?