One-third of Whitehall's civil servants - some 25,000 people - should be relocated outside London to help drive devolution, a new report has recommended.
The report from right-of-centre think-tank Policy Exchange argued that placing thousands of London-based civil servants in city regions and local authorities around the UK would boost productivity and innovation in public service delivery.
Its author, Damian Hind, said it was time for Theresa May to end the "outdated Sir Humphrey model of government" in favour of a "bottom-up and localised approach" to solving problems in services like health, welfare, criminal justice and education.
He called for local areas to be given complete freedom to set public sector pay, allowing different rates to be established for the same job in different parts of the country.
And he said new budget flexibilities should be introduced to allow local areas to experiment with new financing models.
"Our top-down and centralised system of government makes it difficult for any political party to deliver the type of radical public service reforms needed to increase growth and living standards across Britain," said Mr Hind.
"Change still seems to start with diktats from Whitehall. If we truly want to create public services that help people to live independent and fulfilling lives then we need to think differently about how we design and deliver services. More decent, human and caring services will only be achieved by changing the mindset of policymakers in Westminster, breaking down the outdated Sir Humphrey model of Government and putting local places firmly in control."
Around 20,000 civil service posts were moved out of London between 2004 and 2010 following the Government-commissioned Lyons review, but around 80,000 civil servants remain in the capital - including 70% of those in senior roles.