https://www.familysearch.org/en/wiki/The_Parliamentary_Archives_(U.K.)National Collections

Bevan, Amanda, (Ed.). Tracing Your Ancestors in the Public Record Office (6th ed.), The National Archives. [ISBN 1903365341] 
["This is a new, revised edition of the best-selling guide. Now in its sixth edition, Tracing Your Ancestors in the Public Record Office continues to provide comprehensive guidance to all researchers, new or experienced, wishing to trace their forebears among the records of government or courts held at The National Archives. It leads the reader through the census and military service records, wills and lawsuits, court rolls and hearth taxes and all other records where our ancestors may have left their tracks. . . this new revised edition provides information on this and many other releases of records at the National Archives, including army, navy, merchant navy and immigration records. New information about how to access the records via the catalogue is also provided."]

• The National Archives (TNA) in Kew brings together the Public Records Office (PRO) and the Historical Manuscripts Commission, and is the principal repository for English and Welsh records. ( Note: most Scottish records are held in the National Archives of Scotland in Edinburgh, and Northern Ireland Records are held by The Public Record Office of Northern Ireland (PRONI) .)
• Now that the Access to Archives (A2A) project is no more, TNA's  Discovery catalogue covers holdings in many regional archives as well as the National Archives themselves - see their  Find an Archive page. (To search all these other archives use the "Held By" option in the catalogue's Advanced Searchfacility.)
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  • Copies of the National Archives' Research Guidesare now available online, as is their very useful catalogue.
  • Research Guides to Online Collectionsat the National Archives.
  • The National Archives' Looking for a Person?resource listing - "Each guide tells you where you can find, access and understand the relevant records".
  • Their Manorial Documents Registeridentifies the location of manorial documents.
  • Your Archives- "The National Archives' online community of records users", a wiki that archive users could contribute to - now closed.
  • The National Archives publishes a useful free enewslettergiving a "monthly round-up of news, blogs, offers and events ".
  • They also have a YouTube channel of videos providing tips on using the Discovery catalogue, visiting, etc.
• Quick animated guidesto using the National Archives.
• The British Library'scollections may be regarded as the world's finest; the range and effectiveness of the services it provides on the basis of these collections are without rival. Their web pages give access to their comprehensive online cataloguesincluding the British Library Public Catalogue, as well as providing full details of the library's services and facilities.
• The Church of Jesus Christ of Latter-day Saints offers a wide range of genealogical resources at its Family History Centers around the world.  For contact details,  click here and search for the centre nearest you.

Listings and Guides

• The National Archives' "gateway to archival resources, projects and initiatives in the UK and abroad" has been transferred to the UNESCO Archives Portal (archived copy).
• JISC's  Library Hub Discover provides a means of  searching resources in UK and Irish academic, national & specialist libraries - as of Jan 2020, it held  "42,377,775 records created from 106,728,673 records contributed by 144 institutions".
• The Archives Hubis a service run by MIMAS at Manchester Computing which provides free access to descriptions of archives held in the UK's universities and colleges. The descriptions can be searched in a number of ways and will form one part of the emerging UK National Archives Network.
• LDS Family History Centres.
• Culture 24, "Latest news, exhibition reviews, links, listings and education resources from thousands of UK museums, galleries, archives and libraries, all in one place".
• Details of 1600 Museums, Galleries and Historic Housesprovided by Britains Finest.
• UK250's listing of  UK museum websites (archived copy)
• Details of Maritime and Naval Museumsin Britain and Ireland provided by Dr Martin H. Evans and Dr Janet West. A Location Mapis also available.
• The British & Irish Archaeological Bibliography- "The biab online database contains datasets covering publications from AD 1695 to the present day on archaeology and the historic environment, historic buildings, maritime and industrial archaeology, environmental history, and the conservation of material culture" - nearly 200,000 references, as of June 2007.
• Community Archives- set up on behalf of the National Council on Archives "to show the variety and quantity of community archives in the UK."
• UK Parliamentary Archives - FamilySearch guide.section.

Specialist Collections

• Society of Genealogists
• Institute of Heraldic and Genealogical Studies,
• The Methodist Archives and Research Centreis part of the John Rylands University Library of Manchester.
• The Huguenot Libraryis located at University College, London
• The Royal Archives - subscription access via Find My Past.
• The The British Postal Musem and Archive(formerly Post Office Archives and Records Services) holds the records of the British Post Office from the 17th century to the present day.
• Institute for Historical Research
• India Office(archived copy): Family History Research.
• The British Empire and Commonwealth Museum.
• The Women's Library- "housing the most extensive collection of women's history in the UK".
• The National Gas Archive- "The NGA holds up to two kilometres of records covering the history and development of the UK gas industry. The records date from about 1812 to the present day and include many of the administrative, financial, legal, technical, property and personnel records of the industry."
• The National Army Museum.

Miscellaneous

• Association of Independent Libraries- details of member institutions and publications.