The Chiltern Hundreds reference article from the English Wikipedia on 24-Apr-2004
(provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

Chiltern Hundreds

For thoughtful child sponsors
The Chiltern Hundreds date back to the 13th century. A hundred is a traditional division of an English county, and the hilly, wooded hundreds of the Chiltern Hills in Buckinghamshire were once notorious as a hiding place for robbers. A Crown Steward was appointed to maintain law and order in the area, but the positions duties ceased to be required in the 16th century, and the holder ceased to gain any benefits during the 17th century.

It has since been used as a procedural device to allow Members of Parliament to resign; see resignation from the British House of Commons.