| Labour Campaign for Electoral Reform | (1 collection) |
| Labour History Archive and Study Centre | (2 collections) |
| Labour History Archive and Study Centre (People's History Museum/University of Central Lancashire) | (10 collections) |
| Lambeth Archives Department | (2 collections) |
| Lambeth Palace Library | (18 collections) |
| Langdon Down Trust | (2 collections) |
| Law Centres Federation | (1 collection) |
| League Against Cruel Sports | (1 collection) |
| League for the Exchange of Commonwealth Teachers | (1 collection) |
| Leeds University Library, Special Collections | (1 collection) |
| Legal Action Group | (1 collection) |
| Leicestershire, Leicester and Rutland, Record Office for | (1 collection) |
| Leonard Cheshire Archive | (1 collection) |
| Leprosy Mission | (1 collection) |
| Lesbian and Gay Christian Movement | (1 collection) |
| Lewisham Local History and Archives Centre | (1 collection) |
| Linen Hall Library | (2 collections) |
| Liverpool Record Office | (3 collections) |
| Liverpool University: Special Collections and Archives | (10 collections) |
| London Metropolitan Archives | (1 collection) |
| London Metropolitan Archives: City of London | (46 collections) |
| London Metropolitan University, The Women's Library | (3 collections) |
| London Metropolitan University, Women's Library | (1 collection) |
| London Metropolitan University: The Women's Library | (61 collections) |
| London Metropolitan University: Trades Union Congress Library Collections | (3 collections) |
| London School of Economics Library, Archives Division | (2 collections) |
| London University: Goldsmiths College | (1 collection) |
| London University: Institute of Commonwealth Studies | (1 collection) |
| London University: Institute of Education | (7 collections) |
| London University: Kings College Archives | (4 collections) |
| London University: London School of Economics Library, Archives Division | (58 collections) |
| London University: Royal Holloway and Bedford New College | (1 collection) |
| London University: School of Oriental and African Studies Library | (9 collections) |
| London University: UCL School of Slavonic and East European Studies | (1 collection) |
| London University: University College London (UCL) Special Collections | (3 collections) |
| Lord's Day Observance Society | (1 collection) |
| Manchester Archives and Local Studies | (4 collections) |
| Manchester University, John Rylands Library | (1 collection) |
| Manchester University: John Rylands Library | (3 collections) |
| Manchester University: Methodist Archives and Research Centre | (1 collection) |
| Marx Memorial Library | (2 collections) |
| McMaster University Library | (1 collection) |
| Medical Mission Sisters Generalate Archives | (1 collection) |
| Mental Health Foundation | (1 collection) |
| Merseyside Record Office | (1 collection) |
| Middlesex University, Bernie Grant Archives | (1 collection) |
| Middlesex University: Information Learning Resources Services | (1 collection) |
| Museum of English Rural Life | (1 collection) |
| Muslim Council of Britain | (1 collection) |
| National Archives of Scotland | (6 collections) |
| National Army Museum, Department of Archives Photographs Film and Sound | (1 collection) |
| National Association for Environmental Education | (1 collection) |
| National Association of Prison Visitors | (1 collection) |
| National Campaign for Nursery Education | (1 collection) |
| National Childminding Association | (1 collection) |
| National Children's Bureau | (1 collection) |
| National Consumer Federation | (1 collection) |
| National Council of Voluntary Child Care Organisations | (1 collection) |
| National Institute of Economic and Social Research | (1 collection) |
| National League of the Blind and Disabled | (1 collection) |
| National Library of Scotland, Manuscript Collections | (20 collections) |
| National Library of Wales: Department of Collection Services | (25 collections) |
| National Monuments Record | (1 collection) |
| National Society for Clean Air and Environmental Protection | (1 collection) |
| National Society for the Prevention of Cruelty to Children | (2 collections) |
| National Trust | (1 collection) |
| Newcastle upon Tyne University: The Robinson Library | (1 collection) |
| Norfolk Record Office | (2 collections) |
| Northamptonshire Record Office | (1 collection) |
| Order of St John Library and Museum | (1 collection) |
| Oxfam Archive | (1 collection) |
| Oxford University: Bodleian Library of Commonwealth and African Studies at Rhodes House | (13 collections) |
| Oxford University: Bodleian Library, Special Collections and Western Manuscripts | (12 collections) |
| Oxford University: Harris Manchester College Library | (1 collection) |
| Oxford University: Regent's Park College, Angus Library | (2 collections) |
| Oxford University: St Antony's College: Middle East Centre Archive | (3 collections) |
| Oxfordshire Record Office | (1 collection) |
| Parliamentary Archives | (7 collections) |
| Peace Pledge Union | (1 collection) |
| Pedestrians Association | (1 collection) |
| Polish Library POSK | (1 collection) |
| Private | (3 collections) |
| Private: Enquiries to The National Archives, National Advisory Services | (2 collections) |
| Public Record Office of Northern Ireland | (19 collections) |
