The Chiltern Hundreds is an ancient administrative area in Buckinghamshire, England, composed of three "hundreds" and lying partially within the Chiltern Hills. "Taking the Chiltern Hundreds" refers to the legal fiction used to resign from the House of Commons. Since Members of Parliament are not permitted to resign, they are instead appointed to an "office of profit under the Crown", which requires MPs to vacate their seats. The ancient office of Crown Steward and Bailiff for the Chiltern Hundreds, having been reduced to a mere sinecure by the 17th century, was first used by John Pitt in 1751 to vacate his seat in the House of Commons. Other titles were also later used for the same purpose, but only the Chiltern Hundreds and the Crown Steward and Bailiff of the Manor of Northstead are still in use.
Three Chiltern Hundreds
A hundred was a traditional division of an English county: the Oxford English Dictionary says that the etymology is "exceedingly obscure". The three Chiltern Hundreds were Stoke Hundred, Desborough Hundred, and Burnham Hundred. Despite their collective name only Desborough Hundred was located within the area defined by the Chiltern Hills in Buckinghamshire. The area had been Crown property as early as the 13th century.
Steward and bailiff
Through the Saxon and early Norman periods the area was administered by an elder. But by the late Middle Ages the office holder was elected from among a hundred's notable landholding families. As the area was wild and notorious for outlaws, a steward and bailiff was appointed directly by the Crown (thus as a royal bailiwick it was a legal office answerable to the reigning monarch) to maintain law and order. However, by the end of the 16th century such positions had been deprecated by changes in local and Crown representations and roles – the government of Elizabeth I had established royal representatives (Justices of the Peace, Sheriffs, and Lords Lieutenant) in every county of England and Wales; they ensured that Royal commands and laws were obeyed. By the 17th century the office of steward and bailiff had been reduced to just a title with no attached powers or duties.
Resignation from the House of Commons
In the 17th century Members of Parliament (MPs) were often elected against their will. On 2 March 1624, a resolution was passed by the House of Commons making it illegal for an MP to quit or wilfully give up his seat. Believing that officers of the Crown could not remain impartial, the House passed a resolution on 30 December 1680 stating that an MP who "shall accept any Office, or Place of Profit, from the Crown, without the Leave of this House ... shall be expelled [from] this House." However, MPs were able to hold Crown Stewardships until 1740, when Sir Watkin Williams-Wynn was deemed to have vacated his Commons seat after becoming Steward of the Lordship and Manor of Bromfield and Yale.
The post of Crown Steward and Bailiff of the three Chiltern Hundreds of Stoke, Desborough and Burnham remained a nominal office of profit under the Crown, even though it had lost its original significance. It became the first office to be used for resignation when John Pitt was appointed Crown Steward on 25 January 1751. A number of other offices have also been used, but only the Chiltern Hundreds and the Crown Steward and Bailiff of the Manor of Northstead are still in use.