Ms Reynolds added: “I see benefits for those who want to have the flexibility to work part-time. I’m a mother of two young children. Sometimes I wish I could work part-time.”

“But in general I don’t think civil servants should work four days instead of five as a general rule.”

A survey of 1,200 staff carried out by Defra economists and published by the public service’s largest union, PCS, said a shorter working week would reduce annual staff turnover by 57 per cent and reduce annual sick days by 65 per cent.

The study said this would save taxpayers £21.4 million a year, roughly equivalent to the department’s flood defense budget for Northumbria.

Union leaders are meeting ministers on Thursday to discuss the findings and push for a four-day week pilot.

The PCS is expected to conduct further research into how a four-day week would work in practice at Defra.

PCS general secretary Fran Heathcote said: “We have long been discussing the social, practical and professional benefits of the four-day week. Now this research also shows financial benefits.

“It also suggests that any opposition to employees working four days a week is purely ideological. Why else would an employer stand in the way of progress?

“Our members are steadfast in their belief that a four-day week is critical to achieving a good quality of life, improving their health and well-being, and helping them meet their caregiving responsibilities while increasing their productivity at all times.”

A Defra spokesman said: “There are no plans for a four-day working week.”