The rule emerged from the turbulent politics of the early 17th century and the growing struggle between Parliament and the Crown. At the time, serving as an MP was often seen less as an honour and more of an obligation. MPs who displeased the Monarch could face severe consequences, including the scaffold. Some preferred to resign rather than risk confrontation with the King.

Parliament, however, feared that allowing easy resignation would leave MPs vulnerable to royal pressure and weaken the independence of the Commons. Preventing resignation was a way of protecting Parliament’s authority.

A second key development came in December 1680, when the Commons resolved that any MP accepting an “office or place of profit” from the Crown – that is, a paid post – would automatically lose their seat. This reflected concern that MPs receiving money or favour from the Monarch might place loyalty to the Crown above loyalty to Parliament.

Neither the 1623 nor the 1680 resolutions has ever been repealed. The House of Commons Disqualification Act 1741 later formalised which offices were incompatible with Commons membership. The House of Commons Disqualification Act 1975 preserved the arrangement and has subsequently been amended from time to time to keep up with related developments. It provides that, during the lifetime of a Parliament, a seat in the House of Commons will normally become vacant only if an MP:

• dies;

• is expelled after being disqualified for bankruptcy

• is expelled for treason,

• is imprisoned for more than a year or is the subject of indefinite detention;

• is elevated to the Peerage;

• is elevated to a Bishopric;

• is elected as a Police and Crime Commissioner;

• is elected as a member of one of the devolved legislatures in Scotland, Wales or Northern Ireland;

• is appointed as a member of the civil service, armed forces, police, or a number of other public posts; or

• loses a successful recall petition under the Recall of MPs Act 2015.

The full title is The Crown Steward and Bailiff of the three Chiltern Hundreds of Stoke, Desborough and Burnham. The area broadly corresponds to parts of modern Buckinghamshire, including the towns of Amersham, Beaconsfield, High Wycombe Marlow, Eton and Chesham. The Crown Steward and Bailiff administered this royal bailiwick (land run on behalf of the Crown) from at least the 13th century. By the 17th century, however, the office of The Crown Steward had ceased to have any real duties or income. It was first used as a mechanism for resignation from the Commons in 1751, when John Pitt MP sought to vacate his seat of Wareham so he could contest another constituency, Dorchester.

The second office is The Crown Steward and Bailiff of the Manor of Northstead, a much smaller and poorer estate near Scalby in the North Riding of Yorkshire. Victorian County History historians described the Manor’s main property in around 1600 as little more than “an old chamber ... a low house under it, unfit for habitation.” The office was first used as a resignation device in 1844.

An MP wishing to resign - or occasionally to trigger a by-election to stand again or elsewhere – must write to the Chancellor of the Exchequer requesting appointment to one of the two offices of profit. The positions are unpaid and entirely ceremonial. They are alternated so that two MPs can resign at roughly the same time if necessary. The Chancellor formally appoints the office-holder by written warrant, automatically ending the appointment of the previous holder. When the warrant is signed, a letter is sent to the MP, but omitting the letters MP after their name, to tell them that they have been appointed to the office. The Office of the Speaker, the Government and opposition whips are also notified. The MP is thereby legally disqualified from the House of Commons and their seat becomes vacant, triggering a by-election. The appointment/resignation is formally recorded in the London Gazette and in the Votes and Proceedings of the House of Commons, though not in Hansard.

Attempts to modernise the process have repeatedly failed.

One of the earliest came in the 1770s, when George Grenville MP introduced a bill allowing MPs to vacate their seats voluntarily. The proposal was rejected because Prime Minister Lord North feared it would make it easier for MPs to resign and contest by-elections elsewhere as an anti-government candidate.

In the 19th century, Prime Minister William Gladstone also favoured reform. He objected to the idea that appointment to an “office of profit” appeared to confer an honour, even on disgraced MPs. He was particularly irritated by the case of Edwin James MP, who fled to America in the early 1860s while heavily in debt.

Gladstone felt such a figure should not receive even the symbolic distinction of appointment to the Chiltern Hundreds. In practice, the issue was sidestepped simply by no longer describing the appointment as an honour.

More recently, in 2011, Hilary Benn MP asked whether it was time to replace the fiction with a straightforward resignation letter sent to the Speaker. The Leader of the House of Commons, Sir George Young MP, replied that the existing arrangement “has served us well for 260 years” and that the Government had no plans to change it.