The first two sections of this manuscript, the 'Extent of Anglesey and Caernarvon' were compiled by John de Delves, the deputy-justice of north Wales, in 1352. The manuscript is more commonly known as the 'Record of Caenarvon' as the folios relating to Caernarfonshire were edited by Sir Henry Ellis and published in 1838. The third section of the manuscript, relating to Merionethshire, is of a later date and was compiled in the early fifteenth century. The manuscript is regarded as one of the most important sources for the economic and social history of medieval Gwynedd. It provides a detailed description of the rents and services which were due to the ruler or lord from his tenants and possessions in each commote. A selection of the folios from the surveys of Anglesey and Merionethshire are shown here.