Anglo-Catholic History Society:
http://www.achs.org.uk/
American Society of Church History: http://www.churchhistory.org/
Association of British Theological And Philosophical Libraries:
http://www.abtapl.org.uk
British Association for Local History: http://www.balh.co.uk/
Canterbury and York Society: https://www-users.york.ac.uk/~cf13/
Catholic Historical Society of Ireland:
http://www.archiviumhibernicum.ie/
Catholic Record Society: http://www.crs.org.uk/
Historical Association: http://www.history.org.uk
Institute of Historical Research: http://www.history.ac.uk
Royal Historical Society: http://www.royalhistoricalsociety.org
Society for Pentecostal Studies: http://www.sps-usa.org
Strict Baptist Historical Society:
http://www.strictbaptisthistory.org.uk
Unitarian Historical Society: http://www.unitarianhistory.org.uk
Wesley Historical Society: http://www.wesleyhistoricalsociety.org.uk
British State Prayers, Fasts and Thanksgivings, 1540s to 1940:
http://www.dur.ac.uk/history/research/research_projects/british_state_prayers/
Building on History: The Church in London:
http://www.open.ac.uk/buildingonhistory
Christianity and Culture: http://www.christianityandculture.org.uk
Victoria County History: http://www.victoriacountyhistory.ac.uk
Warwick Network for Parish Research:
http://go.warwick.ac.uk/parishnetwork
Libraries
Catholic National Library: http://www.catholic-library.org.uk
Dr Williams's Library: https://dwl.ac.uk/
Gladstone's Library: http://www.st-deiniols.com
Lambeth Palace Library: http://www.lambethpalacelibrary.org
Library of the Religious Society of Friends:
http://www.quaker.org.uk/library
The John Rylands Research Institute and Library: https://www.library.manchester.ac.uk/rylands/