The Panama papers reveal tax evasion is a huge international problem. But how can governments clean things up? One way might be by opening things up. In the UK, it is a criminal offence to reveal someone else's tax affairs, but in some countries you can easily discover how much anyone earns and how much they pay in tax, from the prime minister and the richest business leader to the poorest pensioner. It can have a profound effect on business practice and wider society, as business correspondent Jonty Bloom discovers, travelling to Norway. Presenter: Jonty Bloom Producer: Ruth Alexander.