How will health improvements and a declining birth rate, economic uncertainty and political turbulence affect an ageing population in Britain and around the world? There are new challenges here for states and for individuals. How might we re-imagine lives that run four score years and ten, and longer? Harper is Professor of Gerontology at Oxford University and Director of the Oxford Institute of Ageing. She is the author of How Population Change will Transform Our World. On 1 May she will be become the Director of The Royal Institution. Chaired by Guto Harri.