Cash v Plastic

The BBC's John Humphrys test-drives the new British five-pound note by dunking it into a cup of coffee while Tim Halford, managing director for Cardtronics UK & Ireland, the country's largest cash machine operator, tells us why cash still has an important role to play despite the rise in cashless financial transactions.

Meanwhile, Harvard University economist Kenneth Rogoff explains why central banks and the gun lobby in the US are loathe to give up on paper money and Nick Williamson, CEO and founder of Credits, tells us how block-chain software might eventually be used to underpin national currencies. Manuela Saragosa presents.