Seventeen firms and around a thousand staff completed the most recent UK pilot reported in July 2025, and all seventeen continued afterwards. Twelve adopted a four-day week permanently and five chose a nine-day fortnight. In a field where sceptics wait for novelty to fade, unanimity deserves attention, alongside the usual caution that volunteers are not a random sample.
What was reported
Sixty-two percent of staff experienced burnout less often, forty-one percent reported better mental health and forty-five percent higher life satisfaction. Service levels were maintained, which matters because customer results are the least independently measured part of the wider literature. Housing associations in related UK programmes have similarly reported stable satisfaction and response times with staggered cover.
The split between twelve firms on four days and five on a nine-day fortnight is itself instructive. Successful programmes increasingly end with the pattern that fits demand, not a uniform badge. A fortnight pattern that survives is worth more than a four-day promise quietly eroded by on-call expectations.
What they did differently
The common thread matches earlier pilots: preparation before the calendar changed, explicit customer arrangements, and measurement agreed in advance. Firms treated the trial as a redesign with a decision date, published results, and kept leaders visibly inside the model.
For organisations planning a start now, copy the discipline rather than the headline. Baseline first, stagger where customers need cover, track actual hours, and pre-agree the floors that would trigger a fix or a stop. Continuation rates reward that honesty.
Sources
- Alliance News / LSE reporting (July 2025) on the latest UK four-day week pilot: 17 firms continuing, wellbeing and service findings.
- Autonomy UK one-year follow-up (2024) for continuation context.
- Day5Group research brief (2026), customer-outcomes and pilot-design sections.
Day5Group is a consultancy that assists in the transition to a 4 day work week. More about Day5Group · All blog articles