Professor Sir David Spiegelhalter is one of the great communicators of probability and uncertainty. His new book, The Art of Uncertainty, explains how to approach uncertainty, luck, probability and ignorance. Tim Harford talks to Sir David about double yoked eggs, the Bay of Pigs, and his top tips for politicians who want to communicate evidence and uncertainty. Presenter: Tim Harford Series producer: Tom Colls Production co-ordinator: Katie Morrison Sound mix: John Scott Editor: Richard Vadon