Middlesex was a constituency of the House of Commons of the Parliament of England, then of the Parliament of Great Britain from 1707 to 1800, then of the Parliament of the United Kingdom from 1801 until abolished in 1885. It returned two members per election by various voting systems including hustings.

Westminster was a parliamentary constituency in the Parliament of England to 1707, the Parliament of Great Britain 1707–1800 and the Parliament of the United Kingdom from 1801. It returned two members to 1885 and one thereafter.