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.

[2] In July 2021 the Ministry of Housing, Communities and Local Government announced that in April 2023, Cumbria would be reorganised into two unitary authorities.

[3] On 1 April 2023, Allerdale Borough Council was abolished and its functions transferred to the new unitary authority known as Cumberland, which also covers the former districts of Carlisle and Copeland.

[6] Other settlements in the borough included: Abbeytown, Allonby, Aspatria, Bolton Low Houses, Bothel, Brigham, Broughton, Great Clifton, Cockermouth, Crosby, Dean, Dearham, Fletchertown, Flimby, Ireby, Keswick, Kirkbride, Maryport, Mawbray, Plumbland, Seaton, Silloth, Tallentire, Thursby, Waverton, Westnewton, and Wigton.

[18] A map illustrating the area of the parishes is included in an appendix to a document produced by Sustainable Keswick.