via a National Archives Tweet:
There are over 2,000 archive holding institutions in the UK, which make their collections publicly available. The ARCHON Directory which is hosted by The National Archives provides contact details for record offices, libraries and other record collecting institutions throughout the United Kingdom and overseas.
As well as being useful for the general public, the ARCHON Directory is used as the central contacts directory for most of the major UK networking projects, including the National Register of Archives (NRA), Access to Archives, AIM25, Archives Network Wales and Archives Hub. It provides archives with a unique repository code which separates them from other services and can be used when undertaking ISAD (G) compliant cataloguing and when contributing to networks.
The data behind this implementation of ARCHON was produced in January 2010.
See Also: Web-Based Version of ARCHON Directory
Note: The directory includes 275 repositories in the U.S., 53 in Canada, 30 in Australia, along with repositories in many other countries.