The Chancellor of the Exchequer has appointed Patrick Mercer to be Steward and Bailiff of the Three Hundreds of Chiltern - the process by which a Member of Parliament resigns their seat.
A by-election will take place at a later date in the constituency of Newark.
How an MP vacates their seat
A resolution passed by the House of Commons on 2 March 1624 prohibits MPs directly from resigning their seats.
Death, disqualification and expulsion are the only means by which a Member’s seat may be vacated during the lifetime of a Parliament.
An MP who wishes to resign has to go through the process of accepting a paid office of the Crown, which automatically disqualifies the MP from holding a seat in the House of Commons.
If an MP indicates that they wish to resign, the Chancellor of the Exchequer grants either the Crown Steward and Bailiff of the Chilterns Hundreds or Crown Steward and Bailiff of the Manor of Northstead by means of a written warrant, in the presence of a witness.
The Member retains the position until the Chancellor appoints another applicant or until the holder applies for release from it. Every new warrant issued revokes the previous holder. It is usual to grant the offices alternately, as this enables two Members to retire at the same time.
House of Commons Library analysis
The House of Commons Library produces briefing papers to inform MPs and their staff of key issues. The papers contain factual information and a range of opinions on each subject, and aim to be politically impartial.
The Library has published a briefing paper on resignation from the House of Commons which contains more information on the history of the Chiltern Hundreds and Manor of Northstead.
Image: PA/Dominic Lipinski
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