Employees will get 100% pay for 80% of the hours they would usually work, with the aim of being more productive 

About 70 companies are taking part in what is thought to be the world's biggest pilot scheme into the working pattern 

The experiment has been organised by a group campaigning for a shorter working week, but for no loss in wages 

Academics from Oxford and Cambridge universities, as well experts at Boston College in the US, will manage the experiment in partnership 

Companies ranging from office-based software developers and recruitment firms to charities and chip shop are taking part 

Clare Doherty, who helps run the office for the firm, said the trial is "fantastic" and part of a "natural progression of how we work" 

Girling Jones, a small construction recruitment firm in Exeter switched to a four-day week in January, but has also signed up to the trial 

Productivity is up and so are profits, the boss and company founder Simon Girling said