This article documents the strengths of political parties in the 333 local authorities of England, 32 local authorities of Scotland, 22 principal councils of Wales and 11 local councils of Northern Ireland. England's 333 local authorities are made up of: 32 London borough councils, 24 county councils and 181 district councils (two tiers of local government which share responsibility for the same physical area), 36 metropolitan district councils and 58 unitary authorities, plus the sui generis City of London Corporation and Council of the Isles of Scilly. This article does not cover the Greater London Authority or the 10 combined authorities of England (and their respective mayors). It also doesn't cover the 35 police and crime commissioners or the four police, fire and crime commissioners in England and Wales. And it also doesn't include the thousands of parish/local councils of England, community councils of Scotland and community councils of Wales. English local authorities have a choice of executive arrangements out of a mayor and cabinet executive, a leader and cabinet executive, a committee system or alternative arrangements approved by the Secretary of State. Councils in England and Northern Ireland run on four year cycles, while councils in Scotland and, from 2022, in Wales run on five year cycles. An English local authority's councillors may be elected all at once, by halves or by thirds. Because of this disparate system, various local elections take place every year, but changes in party representation arise frequently regardless due to resignations, deaths, by-elections, co-options and changes of affiliation. (en)