More than 3,300 workers at 70 UK companies, ranging from a local chippy to large financial firms, start working a four-day week from Monday with no loss of pay in the world’s biggest trial of the new working pattern.

The pilot is running for six months and is being organised by 4 Day Week Global in partnership with the thinktank Autonomy, the 4 Day Week Campaign, and researchers at Cambridge University, Oxford University and Boston College.

The trial is based on the 100:80:100 model – 100% of pay for 80% of the time, in exchange for a commitment to maintain 100% productivity.

Platten’s Fish and Chips in Wells-next-the-Sea on the north Norfolk coast is participating, along with the Sheffield software firm Rivelin Robotics, the London-based inheritance tax specialists Stellar Asset Management, and Charity Bank in Tonbridge, Kent.

Joe O’Connor, chief executive of the not-for-profit group 4 Day Week Global, said the UK was at the crest of the four-day week wave: “As we emerge from the pandemic, more and more companies are recognising that the new frontier for competition is quality of life, and that reduced-hour, output-focused working is the vehicle to give them a competitive edge.”

Some of the other companies involved provide education, workplace consultancy, housing, skincare, building and construction recruitment services, food and beverages, and digital marketing.

Researchers will work with each participating organisation to measure the impact on productivity in the business and the wellbeing of its workers, as well as the impact on the environment and gender equality.

Government-backed four-day week trials are also due to begin later this year in Spain and Scotland.

Juliet Schor, a professor of sociology at Boston College and lead researcher on the pilot, described it as a “historic trial”. “We’ll be analysing how employees respond to having an extra day off, in terms of stress and burnout, job and life satisfaction, health, sleep, energy use, travel and many other aspects of life,” she said.

“The four-day week is generally considered to be a triple-dividend policy – helping employees, companies, and the climate. Our research efforts will be digging into all of this.”

Wyatt Watts, 25, team leader at Platten’s Fish and Chips, said: “When I first heard we were going to be working less hours with the same pay, I thought to myself, ‘What’s the catch?’ Usually I’m so exhausted from work I don’t have the energy, so hopefully having that extra time to rest will boost my energy levels.”

He said the decision to join the pilot was already having an impact. “Morale has improved and we’re hoping that our productivity at work is going to be higher.”

Ed Siegel, chief executive of Charity Bank, said it was proud to be one of the first banks in the UK to embrace the four-day week. “We have long been a champion of flexible working, but the pandemic really moved the goalposts in this regard. For Charity Bank, the move to a four-day week seems a natural next step.

“The 20th-century concept of a five-day working week is no longer the best fit for 21st-century business. We firmly believe that a four-day week with no change to salary or benefits will create a happier workforce and will have an equally positive impact on business productivity, customer experience and our social mission.”