Publishers
- The Medlar Press 8
- The Mendip Press 1
- The Mercat Press 1
- The Mercian Publishers 1
- The Merthyr Teachers Centre Group 1
- The Metals Society 1
- The Metropolitan Museum of Art 6
- The Mid Northumberland Arts Group 1
- The Middlesex County Record Society 4
- The Midland Educational Company 1
- The Military Press 1
- The Mining Research Group 2
- The Mission Foundation 1
- The MIT Press 2
- The Monmouth Historical and Educational Trust 1
- The Monmouthshire Golf Club 1
- The Motor World Publishing Co. Ltd. 7
- The Museum of Modern Art 1
- The National Archives Of India 1
- The National Assembly Of Wales 2
- The National Audubon Society 2
- The National Gallery Of Art, Washington 4
- The National Library of Wales 6
- The National Magazine Co. Ltd. 2
- The National Sunday School Union 2
- The National Traction Engine Club Ltd. 1
- The National Trust 1
- The National Trust For Scotland 1
- The Natural History Press 1
- The Natural History Society Of Northumbria 1
- The Natural Science Association Of America 1
- The Naval & Military Press Ltd. 7
- The Nettlebed Press 1
- The New American Library 1
- The New-York Historical Society 1
- The Newcomen Society 2
- The Newport Printing Co. 3
- The Newstead Press 1
- The Nonesuch Press 2
- The North Eastern Railway Association 7
- The Northern Publishing Co. Ltd. 1
- The O'Brien Press Ltd. 3
- The Oakwood Press 35
- The Old Felstedian Society 2
- The Old Leysian Union 1
- The Old Monmothian Club 1
- The Old Pauline Club 1
- The Old Rugbeian Society 1
- The Original Double Red Ltd. 1
- The Ornithological Society Of Japan 1
- The Owl Press Ltd. 1
- The Oxford Illustrated Press 4
- The Packard Humanities Institute 1
- The Paddle Steamer Preservation Society 1
- The Page Company 1
- The Paternoster Press Ltd. 1
- The Paterson Engineering Co. Ltd. 1
- The Penguin Group 13
- The Penn Publishing Company 1
- The Pennsylvania State University Press 1
- The Pentland Press 2
- The Peppertree Press 1
- The Pequot Press 1
- The Perth Printing Company 1
- The Pet Book Publishing Company Limited 1
- The Pevensey Press 1
- The Physical Society 1
- The Pierpont Morgan Library 1
- The Pilgrim Press 4
- The Pilgrim Press Limited 1
- The Pilot Press Ltd. 1
- The Plane Picture Co. Publishing 2
- The Platt And Munk Co. Inc. 2
- The Porcupine's Quill 1
- The Port Of Bristol Authority 1
- The Potato Press 1
- The Pragmatic Bookshelf 2
- The Pre-War Austin Seven Club Ltd. 1
- The Provincial Grand Lodge Of Middlesex 1
- The R.S. Surtees Society 2
- The R.T.S. Office 2
- The Radcliffe Press 2
- The Raf Cranwell Aircraft Apprentices Association 2
- The Railway Correspondence And Travel Society 19
- The Railway Gazette 1
- The Railway Publishing Co. Ltd. 5
- The Ranelagh Press 1
- The Ray Society London 1
- The Readers Library Publishing Co. Ltd. 3
- The Rector Of Jarrow 1
- The Regensteiner Corporation 1
- The Regimental Trust 10th Princess Mary's Own Gurkha Rifles 1
- The Reilly & Britton Co. 1
- The Religious Tract Society 24
- The Richards Press 4
- The Richards Press Ltd. 23
- The Richmond Publishing Co. Ltd. 1
- The Rifle Brigade Club And Association 1
- The Rissingtons Local History Society 1
- The Rockingham Press 2