Smile. Historian and author Kate Williams goes in search of the modern winning smile. The wide and toothy smile is all around us and used in many different and persuasive ways, from the delight of meeting up with friends, beautiful people beaming down from billboards persuading us to buy their product, to politicians vying to win our votes, the broad and confident smile is very much at the centre of communication in today's society. However this hasn't always the case, with open mouthed smiling deemed a sign of madness and undignified. We discover the impact of dentistry and films on our changing relationship with our smiles, the role gender and culture play, why most of us hate smiling in photographs and Jenni Murray explains why she would never broadcast without one. Producer: Andrea Kidd.