The process of making such inquisition was effected by the royal escheators in each county where the deceased held land.
was made in 1236, in the reign of King Henry III (1216–1272), and the practice ceased c. 1640, at the start of the English Civil War, and was finally abolished by the Tenures Abolition Act 1660, which ended the feudal system.
If the tenant-in-chief was found to have no heir, for example if he was unmarried or childless, the lands held would "escheat" (i.e. revert to the demesne of the king) to be re-granted as a valuable reward to a favoured courtier or official, or sold for cash proceeds.
If the tenant-in-chief left a minor son as heir, that is to say one aged under 21, his wardship escheated likewise to the king, who was able to sell or award his marriage to a third party.
This exempted him from the scope of the Inquisition post mortem, as the legal holders were effectively an immortal corporation one or two of whose constituent feoffees could on occasion die, only to be replaced by others.
He himself, or his relatives if a minor, would generally inform the king's chancery that the death had occurred,[2] and this would prompt the production of a writ by the chancery under the king's great seal addressed to the various escheators of the counties in which the deceased held lands, known as a writ diem clausit extremum.
On receipt of the writ the escheator requested the sheriff of the county concerned to empanell a jury made up of local freeholders, that is to say persons of social standing, who could be relied upon to provide the standard information required in accurate form.
All revenues resulting from such lands whilst in the hands of the escheator had to be audited (i.e. accounted for before the Barons of the Exchequer) periodically at the treasury.
The original return was held in the records of the chancery, to which department the escheator had made his original return, the other by the treasury, which had caused a copy to be made for fiscal purposes, in order to verify the escheator's accounts[5] which were presented to the treasury periodically.
Unlike some other series of records, they were not historically sewn together as rolls, but in modern times the parchment sheets have been bound in files with covers, and are today held at the National Archives in Kew.
20, 6–10 Henry V, of the Calendar of Inquisitions Post Mortem, illustrates many common elements: Writ 24 July 1422.
By an indenture of 26 Oct. 1418, shown to the jurors, William Tauk, Robert Monkeston and Thomas Welegh, who were seised in their demesne as of fee, granted the manor of Pury, a messuage, carucate and 13 acres meadow, 40 a. pasture and 20 a. wood at "la Bere juxta Southwyke" as lands and tenements in Pury, Badley, "Colvyle", "Holdmede", and "Bere", to William Pagam and his wife Agnes, who survives, for life of Agnes, remainder to William and his heirs in fee simple.
In 1865 two volumes were published, covering the reigns of Henry III and Edward I, in a new series edited by Charles Roberts entitled Calendarium Genealogicum, which concentrated on providing the names of heirs omitted from the previous publications, designed to be of particular use to genealogists.
Winchester University and the Department of Digital Humanities at King's College London are currently working on a project to publish on-line in searchable format a revised and expanded series of all existing texts covering the years 1236–1447 and 1485–1509.