 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.The changes caused the ceremonial counties to be defined separately, as they had been before 1974.