The proposed combined authority would be led by a directly elected mayor.

Through an expression of interest letter to government, leaders will set out a shared ambition to secure new powers and funding.

They believe it would enable the region to deliver more integrated plans for transport, housing, and economic development, with a particular focus on social housing, and inclusive growth.

Councillor Liz Leffman, leader of Oxfordshire County Council, said: "We have a once in a generation chance to seize the opportunities that public sector reform and devolution offers.

"A Thames Valley MSA will harness the collective strengths of the region to unlock unparalleled prospects for inclusive and sustainable growth together with coherent regional planning for housing, transport, and economic development.

"It provides a unique opportunity to shape our urban and rural places, ensuring lasting benefits for current and future generations."

The authority, if approved, could unlock up to £18.7 billion for the Thames Valley economy by 2040 and generate an estimated £7 billion in additional annual tax revenue.

The proposal is currently being debated by councils across the region, with an expression of interest expected to be submitted to the government by the end of the year.

Councillor David Hingley, leader of Cherwell District Council, said: "Cherwell fully supports the rationale for a Thames Valley mayoral strategic authority.

"Devolution done right offers a real opportunity to secure faster investment, provide a strong voice for our area, and drive joined-up decision-making.

"By working together across the Thames Valley, we can achieve greater impact and long-term benefits for residents and businesses throughout Cherwell, Oxfordshire, and the wider region."

The proposed MSA would not take over day-to-day public services, which would continue to be delivered by existing councils.

Instead, it would focus on strategic regional priorities and attract larger-scale investment.

Councillor Susan Brown, leader of Oxford City Council, said: "The Thames Valley already leads in research and innovation.

"With the right leadership, powers, and funding, we can unlock even more of that potential – creating jobs not only in science and tech, but across logistics, education, hospitality, and beyond.

"London and Manchester have secured major infrastructure improvements through mayoral strategic authorities, particularly in transport.

"Oxford deserves those same opportunities."

The Thames Valley MSA will be designed to attract investment and strengthen one of the UK’s most productive and innovative regional economies.

The ambition is for a strategic growth partner for neighbouring authorities where joint working will be beneficial, for example related to the Oxford – Cambridge corridor.

Discussions on the proposed authority have included councils from Oxfordshire, Berkshire, and Swindon.

Detailed proposals will be developed in the coming months, subject to ongoing discussions with government, for consideration by local councils and partners.