This Act of 1543 also established the courts of Great Sessions in Wales, which were equivalent to the English Assizes. The Great Sessions continued until 1830 when they were abolished and an Assizes system was established along English lines. The records for the Great Sessions are held at the National Library of Wales in Aberystwyth; the records for the Assizes are at the Public Record Office in London.
The Quarter Sessions records for Powys start later than 1543: Breconshire has sessions rolls from 1690, Montgomeryshire from 1719 and Radnorshire from 1753. By this time the Justices had begun to act in a more executive capacity. They were concerned with determining judicial cases (though not felonies which were dealt with at Assize); administration of local government; and the statutory enrolment and registration of documents not directly related to the court.
During the nineteenth century a change took place, as standing committees evolved to deal with specific functions, e.g. gaols and bridges. Administrative officers were appointed, the County Treasurer, Surveyor or Bridgemaster, Inspectors of Weights and Measures.
Many administrative functions were transferred to other bodies, e.g. Poor Law in 1834, and highway administration in 1835. The establishment of County Councils under the Local Government Act of 1888 left the Quarter Sessions with purely judicial functions. Finally, under the Courts Act of 1971 Quarter Sessions and Assizes were replaced by Crown Courts administered by central government.