A ministerial by-election is a by-election to fill a vacancy triggered by the appointment of the sitting member of parliament (MP) as a minister in the cabinet. The requirement for new ministers to stand for re-election was introduced in the House of Commons of Great Britain in 1707 and also featured in Westminster system parliaments modelled on it. In latter times, the by-election was usually a formality, uncontested by the opposition. In the United Kingdom, ministerial by-elections were abolished as an anachronism in 1926. The Irish Free State, Union of South Africa, and Dominion of New Zealand never had them.