Excerpt: At present, most workers have to opt in to retirement-saving plans. With automatic enrolment, they have to opt out. This flick of the switch makes pension saving the default option while retaining the voluntary principle. The simplicity of the policy is deceptive. It is grounded in some quite subtle findings of behavioural finance. This branch of economics, which draws upon psychology and experiments, shows that people are not always rational, especially when it comes to saving.