HMC Reading Room ©TNA
The Historical Manuscripts Commission (HMC, formally known as The Royal Commission on Historical Manuscripts) was established in 1869, with a remit to survey and publish original records of 'Institutions and Private Families'. It thus performed a similar function with regard to private archives as the Public Record Office (PRO) did for official papers. Its publications of surveys and calendars were the major raw material for historians until the opening up of local depositories between the 1950s and 1970s, and the HMC also oversaw the maintenance of the National Register of Archives (NRA) from the latter's establishment in 1945. The HMC and the PRO merged to form The National Archives (TNA) in 2003.