The South Yorkshire Mayoral Combined Authority is a formal membership of councils. Formed in 2014, the constituent members of the Mayoral Combined Authority are Sheffield, Rotherham, Barnsley and Doncaster councils. The councils of Bassetlaw, Chesterfield, North East Derbyshire, Derbyshire Dales and Bolsover are ‘non-constituent’ members.
https://governance.southyorkshire-ca.gov.uk/mgCommitteeDetails.aspx?ID=137