Population Matters, formerly the Optimum Population Trust, "is the leading population charity in the UK. We campaign to change the way people think about population."
- Simon Ross - Chief executive
Population Matters was founded as the Optimum Population Trust in 1991 by the late David Willey, its first chairman. Its purpose was to collect, analyse and disseminate information about the sizes of global and national populations, and their relations with the carrying capacities of different countries and the quality of life of their inhabitants. It was intended that such information should help people to make informed choices about policies affecting their and their descendants' welfare. Special emphasis was given to the situation in the United Kingdom."  Aims
Population Matters describes its activities as to:
- campaign for the stabilisation and gradual decrease of the population to sustainable levels by voluntary means, globally and within the UK.
- lobby government and international bodies to increase support for reproductive health and other relevant policies.
- engage with the broader developmental and sustainability movement to encourage them to include population in their thinking.
- research matters of population in relation to the environment, sustainability and other issues.
- disseminate this research to the public and interested parties via our website, through the media and at events.
- ask individuals to consider the impact of population size on sustainability and the environment in their decisions on family size.
- Sara Parkin OBE, Chair
- Fiona McKenzie, Maggie Avison, Stephen Bown, Harry Cripps, John Davies, Rebecca Foljambe, Pip Hayes, Anna Hughes, Emma Olliff, Chris Padley, Ascanio Vitale
- Honorary treasurer: Percy Kelland 
Accessed August 2012: 
- Roger Martin, Chair, Nina Clarke, Vice-chair
- Pippa Hayes, Maggie Avison, Stephen G. Bown , Venetia Caine,Harry Cripps, Colin Gallagher, Treasurer
Accessed March 2011: 
- Janet Boston, TV producer, communications and international environment/development specialist; has held senior media and charity positions including CEO of The Thomson Foundation
- Stephen Bown Professor of Laser Medicine at University College London
- Harry Cripps, MA MSc DMS CEng CEnv FIChemE MEI, chemical engineer, energy efficiency consultant and chartered environmentalist
- Colin Gallagher, Chair of a leading UK economic research and strategy consultancy.
- Pippa Hayes, is a full-time general practitioner in Devon and mother of two teenage boys.
- Roger Martin, Chair, was a senior diplomat, resigning 20 years ago; becoming a leading environmentalist in the South-West and serving on many green NGOs and quangos.
- Robin Maynard, Campaigner with extensive experience of working for leading environmental organisations.
- Nick Reeves, OBE Executive Director of the Chartered Institution of Water and Environmental Management (CIWEM) and writer on environmental affairs.
- Alan Stedall, Vice-chair is an IT Director and has led a number of large-scale systems projects for several UK businesses.
Accessed March 2011: 
The following list of patrons is from 2011, but as of May 2020 the only additions included Leilani Münter, Malcolm Potts , Lionel Shriver and Adrian Hayes. People removed included Aubrey Manning and Norman Myers.
- Sir David Attenborough, Naturalist, broadcaster and trustee of the British Museum and Royal Botanical Gardens, Kew; and a former controller of BBC Two.
- Sir Partha Dasgupta, Frank Ramsey Professor of Economics, University of Cambridge
- Paul Ehrlich, Professor of Population Studies, Stanford University
- Jane Goodall PhD DBE, Founder, Jane Goodall Institute, and UN Messenger of Peace.
- Susan Hampshire OBE, Actress and population campaigner
- John Guillebaud, Former Co-chair of OPT, Emeritus Professor of Family Planning and Reproductive Health, UC London. Ex-Medical Director, Margaret Pyke Centre for Family Planning.
- Dr James Lovelock CBE, Scientist and environmentalist known for proposing the Gaia theory that Earth functions as an organism, and author of 'The Revenge of Gaia'
- Aubrey Manning OBE, Emeritus Professor of Natural History, University of Edinburgh
- Norman Myers CMG, Visiting Fellow, Green College, Oxford University, and at Universities of Harvard, Cornell, Stanford, California, Michigan and Texas
- Sara Parkin OBE, Founder Director and Trustee of Forum for the Future and Director of the Natural Environment Research Council and the Leadership Foundation for Higher Education and Head Teachers into Industry.
- Chris Packham, Naturalist, nature photographer, television presenter and author
- Jonathon Porritt CBE, Founder Director of Forum for the Future and Chairman of the UK Sustainable Development Commission.
- Crispin Tickell GCMG KCVO, Chancellor of Kent University, Director of the Policy Foresight Programme at the James Martin Institute, and former UK Permanent Representative on the United Nations Security Council
Expert Advisory Council
- Muhtari Aminu-Kano, Wendo Aszed, Ugo Bardi, Elizabeth Cripps, Patrick Curry, Herman Daly, Edu Effiom, Rebecca Foljambe, Clifford Garrard, Graeme Maxton, Fred Naggs, Jane O'Sullivan, Niki Rust, William Rees, William Ryerson, Jeroen van den Bergh, Peter Wadhams, Judy Ling Wong 
2011 Accessed March 2011: 
- Martin Chilcott, Chief Executive, Place Group.
- Patrick Curry PhD lives in London and lectures in Religious Studies at the University of Kent. He is the author of 'Ecological Ethics: An Introduction', Polity, 2006.
- Martin Desvaux PhD CPhys is a physicist experienced in life assessment techniques for power generation, petrochemical and plant, and formerly a director of ERA Technology and a Trustee of OPT. He now researches ecological issues.
- Rajamani Nagarajah, Health and development consultant to the European Commission and former Director of Population Concern
- John Rowley, Founder/Editor of www.peopleandplanet.net and former Editor, People magazine (International Planned Parenthood Federation)
- William Ryerson (USA), Founder and president of Population Media Center, William Ryerson has worked to promote population stabilisation for four decades, with an emphasis on social change communications.
- Alastair Service CBE, former Chairman of the Family Planning Association
- Valerie Stevens former Co-chair and Chair of OPT
Resources and articles
Related Sourcewatch articles
- Andrew Ferguson, Honorary Editor of the the OPT Journal's research on eco-footprinting and population carrying capacity.
- Professor Chris Rapley CBE, Director, Science Museum, and former OPT Patron
- Lionel Shriver
- Baroness Shreela Flather - new patron as of Nov 17, 2011 
- About Population Matters, accessed 13 March 2011
- About, Optimum Population Trust, accessed April 24, 2008.
- Population Matters Board, organizational web page, accessed May 13, 2020.
- Population Matters Trustees, organizational web page, accessed August 29, 2012.
- Trustees, Population Matters, accessed March 13, 2011.
- Patrons, Population Matters, accessed March 13, 2011.
- Population Mattters Expert Advisory Council, organizational web page, accessed May 13, 2020.
- Advisory Council, Population Mattters, accessed March 13, 2011.