See also: List of British MPs, List of Parliaments of the United Kingdom, MPs elected in the UK general election, 2005, and Number of British MPs

The United Kingdom has members of three different parliaments:

* Members of Parliament (which refers to members of the Parliament of the United Kingdom, abbreviated to MP(s) but only in reference to members of the (lower) House of Commons)
* Members of the European Parliament (MEPs)
* Members of the Scottish Parliament (MSPs) (Elected members of the pre-Union Parliament of Scotland were called Commissioners.)

The Welsh Assembly is not empowered to make primary legislation and forms the Welsh Assembly Government, which unusually combines legislative and executive functions[citation needed]. The National Assembly consists of 60 elected members; they use the English title Assembly Member (AM) or the equivalent Welsh Aelod y Cynulliad (AC), the latter primarily used when referring to this role when conversing in the Welsh language, and is infrequently heard within English speaking discussions. It is increasingly common, however, to see the Welsh Assembly Government referred to as "the Welsh Government" and the Welsh Assembly is increasingly referred to as Senedd in Welsh, the same word as is used for the Westminster Parliament[citation needed].

The Northern Ireland Assembly's 108 members are elected from 18 six-member constituencies on the basis of universal adult suffrage. The constituencies used are the same as those used for elections to the Westminster Parliament. Elected members are known as Members of the Legislative Assembly (MLA). The Assembly has authority to legislate in a field of competences known as "transferred matters". These matters are not enumerated in the Northern Ireland Act 1998. Rather, they include any competence not explicitly retained by the Parliament at Westminster. Uniquely, Assembly legislation is open to judicial review.

Between 1921 and 1973, Northern Ireland was...