A liberty was an English unit originating in the Middle Ages, traditionally defined as an area in which regalian right was revoked and where the land was held by a mesne lord (i.e. an area in which rights reserved to the king had been devolved into private hands). It later became a unit of local government administration. The Local Government Act 1888 led to the ending of the special jurisdictions in April 1889: the Isle of Ely and Soke of Peterborough became administrative counties, while the three remaining liberties were united to their surrounding counties.