The name derives from the ancient region of Allerdale, represented latterly by the two wards of Cumberland, called Allerdale-above-Derwent and Allerdale-below-Derwent, the present borough corresponding largely to the latter with parts of the former. Much of the area during the medieval period was a royal forest subject to forest law.[2]
Elections to the borough council were held every four years with 49 councillors being elected from 23 wards.[11] No party had a majority on the council since Labour lost their majority at the 2003 election. From the 2019 election until abolition in 2023, the council was jointly administered by the Conservative Party and independents.[12] From March 2021 to March 2023 the leader of the council was Mark Johnson, a Conservative.[13]
The term "Derwent Seven Parishes" is used in defining the collecting scope of Keswick Museum, as Keswick is at the heart of the area covered by these parishes.[18]
A map illustrating the area of the parishes is included in an appendix to a document produced by Sustainable Keswick.[19]