Andrew Marr talks to Simon Wessely about the mental health of soldiers serving in Iraq and Afghanistan, and explores why British personnel appear to have fared so much better than their American counterparts. The historian John Stubbs revels in the antics of the Cavaliers - the 17th century dandies and political intriguers, loyal to the king. The experimental physicist Athene Donald argues that science is as creative as the arts, and describes how studying the texture of yoghurt could help the treatment of dementia. And Simon Sebag Montefiore studies the texture of a city - Jerusalem. His epic 3000 year history is a chronicle of faith and power, diversity and co-existence.

Producer: Katy Hickman.