List and Index Society

The List and Index Society (L&IS) is a learned society that publishes editions and calendars of historical records and occasional monographs.

The society was founded in 1965 by Sir Geoffrey Elton and others, with the aim of publishing and distributing "photographic copies of unprinted lists and indexes kept in the Public Record Office, London, (now The National Archives (United Kingdom) and of other unprinted guides and aids to the use of public archives in the British Isles."

More information on the Wikipedia page

The website is