The first records to be received into the new Glamorgan Record Office on 13 September 1939 were two rolls for the court of Quarter Sessions in 1727. The 75th item, on December 12, was the four rolls for 1800. By the time work in the Record Office was suspended in March 1940, over 1100 records of Quarter Sessions and Glamorgan County Council had been accessioned.
Quarter Sessions was a court of law hearing cases originating in the old county of Glamorgan. Magistrates sat as judges with a jury, but it also had administrative responsibilities, for example maintaining certain bridges in the county, running the prisons, the lunatic asylum, and the police force and enforcing the law on licensing and registration.
The historical records of Quarter Sessions, in some cases dating back to the middle ages, were inherited by County Councils in 1889. They were one of the chief reasons for the creation of county record offices (which began in Bedfordshire in 1913) as Councils responded to requests to make the records available for public inspection.
The records of the court form one of the largest collections held by Glamorgan Archives. The minute books start in 1719 and the sessions rolls in 1727, and each series runs almost without a gap until the court was abolished in 1971. Other records forming part of the Quarter Sessions papers include Land Tax Assessments (1766-1831), deposited plans of public undertakings such as canals, railways and gas and electricity schemes, registers of electors and early records of the Glamorgan Constabulary.