Dorset was a county constituency covering Dorset in southern England, which elected two Members of Parliament (MPs), traditionally known as knights of the shire, to the House of Commons of England from 1290 until 1707, to the House of Commons of Great Britain from 1707 to 1800, and to the House of Commons of the United Kingdom until 1832.

Even after the 1832 Reforms, only three of the nineteen elections before 1885 were contested; in the others, the nominated candidates were returned without a vote.

Ashley-Cooper and Sturt both resigned by accepting the office of Steward of the Chiltern Hundreds causing a by-election.

Bankes was appointed Judge Advocate General of the Armed Forces, requiring a by-election.

Sturt was elevated to the peerage, becoming Lord Alington.