The local government secretary, Steve Reed, is seeking to clamp down on councils introducing four-day working weeks after writing to South Cambridgeshire warning that the policy had damaged performance.
Reed told the council, which is the only local authority to formally trial a four-day week for staff, that they risked worsening public services and value for money.
His letter, first seen by the Telegraph, marks the first intervention by the Labour government on shortened working weeks in local government in England.
Reed wrote to Bridget Smith, the council’s Liberal Democrat leader, noting there had been a deterioration in rent collection and repairs by the council.
“The independent report shows that performance declined in key housing-related services including rent collection, reletting times and tenant satisfaction with repairs, especially where vulnerable residents may be affected,” he wrote.
“If social housing is being built by this government and your team are unable to move residents into them so that they are standing empty then I must reiterate my deep disappointment with your conduct.”
The council leader, Bridget Smith, said she was extremely disappointed to have received Reed’s letter, describing the authority as “exceptionally high performing”.
She also disputed Reed’s claim that staff performance had declined. She said her colleagues had done “100% of their work in 32 hours each week” since the four-day week was introduced.
Reed also said it was not in line with government policy for the council to offer 100% pay for 80% of the workload. “I am therefore seeking assurance about the arrangements your council has in place to consider the impacts of your policy and that value for money for residents is being delivered,” he wrote.
“In particular, I would like to understand how the council is seeking to mitigate the impact to those services which have worsened over the course of the four-day working week trial. I would like you to meet with my officials in the coming weeks to provide that assurance.”
Despite Reed’s tough-sounding letter, the government has no legal power to force the council to end the policy. Decisions on working patterns lie with local authorities, meaning ministers can apply pressure but not impose a ban.
A government source said: “We trust councils to run their own affairs in the best interest of their constituents, but we reserve the right to call out behaviour that lets down voters. They deserve more.”
The Guardian understands that ministers reiterated guidance to local authorities discouraging four-day working weeks, telling them they risked undermining service delivery and value for money.
Smith said: “We have delivered an annual saving of almost £400,000, maintained and improved performance, our turnover has decreased by 41% and the number of applications for roles advertised has surged by 123%.
“Where we previously struggled to recruit and retain expert colleagues such as planners, we now have a full planning service which has just published our most ambitious local plan proposals ever, delivering on the government’s agenda to increase housing and jobs in our area. These results speak for themselves.”
She said all key performance indicators, taken from independently assessed data from the trial, showed an improvement or remained the same, “bar three relating to housing … due to factors completely independent of the four-day working week”.
The 4 Day Week Foundation’s campaign director, Joe Ryle, said: “Sometimes it seems like this government is actively seeking ways to be unpopular.
“As hundreds of companies in the private sector have already shown, a four-day week with no loss of pay can be a win-win for both workers and employers. The 9-5, five-day week is a century-old model that no longer fits the way we live and work today.
“This is deeply disappointing from the government. Councils must be allowed to innovate.”
