Dr David Halpern, behavioural scientist and head of Number 10's Behavioural Insights Team, or the 'Nudge Unit', invites you inside the unconventional, multi-million pound saving initiative that makes a big difference through influencing small, simple changes in our behaviour. Using the application of psychology to the challenges we face in the world today, the Nudge Unit is pushing us in the right direction. This is their story.