unitary authority

noun1

1. •
   In local government, a single-tier authority which replaces a two-tier structure. For example, in England, county councils are abolished and their responsibilities are transferred to boroughs and local government districts (but this only applies to some counties, not all). In some cases complete counties, such as Cornwall and Northumberland, are now unitary authorities without any subdivision into local government districts.

   • "The support of Somerset Council (currently in transition to becoming a unitary authority) will be crucial, as they are the statutory planning authority." — 2023