Publishers
- Loewes 1
- Logaston Press 7
- LOM Art 1
- Londini Gothorum 1
- London Borough Of Hammersmith 1
- London County Council 5
- London Docklands Development Corporation 1
- London Midland and Scottish Railway Company 1
- London Missionary Society 1
- London Natural History Society 1
- London Omnibus Traction Society 1
- London Topographical Society 2
- London Transport 3
- London Underground Ltd. (Northern Line) 1
- Lone Pine Publishing 2
- Longacre Press 5
- Longacre Press Ltd. 5
- Longman 14
- Longman And Co. 3
- Longman Group Ltd. 1
- Longman Scientific & Technical 2
- Longman Young Books 7
- Longman, Brown, Green & Longmans 5
- Longman, Green, Longman And Roberts 2
- Longman, Green, Longman, Roberts & Green 1
- Longman, Hurst, Rees And Orme 3
- Longman, Hurst, Rees, Orme And Brown 3
- Longman, Orme, Brown, Green and Longmans 1
- Longman, Rees, Orme, Brown, and Green 2
- Longman, Rees, Orme, Brown, Green & Longman 2
- Longmans 5
- Longmans (Dorchester) Ltd. 1
- Longmans, Green & Co. 58
- Longmans, Green and Co. Ltd. 1
- Lorenz Books 2
- Loring & Mussey 1
- Lothrop, Lee & Shepard Books 1
- Lothrop, Lee & Shepard Co. 3
- Louisiana State University Press 1
- Lourenco Marques 1
- Lovat Dickson Limited 1
- Lovell Reeve 1
- Lowe 1
- Loykey & Lillybit 1
- Lro Publications Ltd 1
- Lucebaits Publishing 1
- Luciano Ferriani Editore 1
- Ludion, Museum 1
- Lufthansa German Airlines 1
- Lugi Reverdito Editore 1
- Lund Humphries 8
- Lutterworth Press 75
- Lynne Rienner 1
- Lynx 1
- Lynx Edicions 8
- Lyons Press 1
- M Press (media) Ltd. 7
- M. & J. Hobbs 2
- M. And J. Hobbs 1
- M. Carey & Sons 1
- M. Macdonald 1
- M. Moreau 1
- M.A. Donohue & Co. 1
- M.D.E. Publications 1
- M.F. Feheley 2
- M.I.P.I. PUBLISHING 2
- M.M. Holloway 1
- Mabecron Books 2
- Mabel Esther Allan 2
- MacDonald 10
- Macdonald & Co. (Publishers) Ltd. 8
- MacDonald & Evans Ltd. 1
- Macdonald and Jane's 9
- Macdonald Futura Publishers Ltd. 1
- Macdonald Orbis 1
- Macdonald Purnell 1
- MacGibbon & Kee 2
- Mackie & Co. Limited 2
- MacMillan 36
- Macmillan & Co. 29
- Macmillan & Co. Ltd. 105
- Macmillan Children's Books 42
- Macmillan London Limited 11
- Macmillan Press Ltd 3
- MacMillan Publishers Ltd. 1
- Macmillan Publishing Co. 7
- Macmillan Publishing Co. Inc. 2
- Macmillan, New York 1
- Madison Press Books 1
- Magdalen College 3
- Magna Books 1
- Magna Press 3
- Magnard 1
- Magpie Publishing 2
- Mainline & Maritime Ltd 3
- Mainstream Publishing 3
- Mainstream Publishing Company (Edinburgh) Ltd. 2
- Mallard Books 1
- Mallard Press 2
- Malta Ornithological Society 1