The islands council areas were unitary council areas dating from 1975, created under the Local Government Act 1973 and notably the only unitary authorities created by the local government reforms of the 1970s in Great Britain; which generally applied a two-tier structure. They did not form districts within the regions of Scotland because their remoteness made it unviable. Hampton, W., Local Government and Urban Politics, (1991)
The Orkney and Shetland areas were also the areas of county councils which were abolished in 1975. The Western Isles area combined areas which were previously within the county council areas of Ross and Cromarty and Inverness-shire.