The world’s largest ever trial of a four-day working week and reduced working time in Iceland was an “overwhelming success” and should be tested in the UK, researchers have said. More than 1 per cent of Iceland’s working population took part in the pilot programme which cut the working week to 35-36 hours with no reduction in overall pay. Joint analysis by think tanks in Iceland and the UK found that the trials, which ran from 2015 to 2019 and involved more than 2,500 people, boosted productivity and wellbeing and are already leading to permanent changes. Icelandic trade union federations, which collectively negotiate wages and conditions for most Icelandic employees, have already begun to negotiate reduced working hours as a result.