 A review in the 1990s was initiated to select non-metropolitan areas where new unitary authorities could be created.The resulting structural changes were implemented between 1995 and 1998.Bristol, Herefordshire, the Isle of Wight and Rutland were established as counties of a single district; the district councils of Berkshire became unitary; the counties of Avon, Humberside and Cleveland were broken up to create several unitary authorities; and a number of districts were split off from their associated counties.