The group was formed in 1995 and serves as a partnership of eleven city councils: Belfast, Birmingham, Bristol, Cardiff, Glasgow, Leeds, Liverpool, Manchester, Newcastle, Nottingham and Sheffield.

The local authorities came together to challenge the centralised nature of the British state[5] by advocating for the devolution of greater freedom and controls.

[10][11] In 2018, Bristol hosted the first meeting of Core Cities Group leaders with combined authority mayors.

[12][10] During the passage of the Localism Act 2011, the group promoted the 'Core Cities amendment' to allow for bespoke decentralisation to its members, which was successfully incorporated.

"[3][18] An interest of the group is the High Speed 2 project to interlink the larger British cities faster.

[22] It was noted by Cardiff council leader Huw Thomas that EU investment out-weight the British Government's city deals.

[23] In 2019, the leaders of the cities in the group sent a letter to Prime Minister May asking her to avoid a no-deal Brexit.