The 'Rex' rolls for the reigns of Edward III, Richard II and Henry IV, being plea rolls kept on the king's behalf, by the keeper of writs and rolls of the Court of Common Pleas, who was appointed by the king.
The word 'Rex' appears at the heads of most of the individual rotuli, and some rolls are labelled 'the king's roll'. After 1345 the rolls usually lack headings, so the dates of some of them are known only approximately. Many of them bear the names of the successive keepers of the writs and rolls, from Peter de Luddington to Robert Mansfield.
A few of the earlier rolls, to 1337 only, include appointments of attorneys as well as pleas. They contain only a small and decreasing fraction of the number of entries which appear in the main series of plea rolls, and do not include posteas recording subsequent proceedings, as the plea roll entries do. They may have been kept as a check that the rights of the crown were being maintained, but that is difficult to confirm from the contents of individual entries and the reason for their compilation is not really known. They probably came to be regarded as unnecessary and ceased to be made up about 1409.