Arena host: Jonathan Dimbleby, presenter and broadcaster including the chair of Any Questions and Any Answers for BBC Radio 4, and documentary film maker: one-time organic farmer, President of the Soil Association and Vice President of the Council for the Protection of Rural England.

• Population, resources and climate change
• Climate change justice: the politics of blame
• Digging for the future
• A sustainable future needs business to drive it
• The age of ageing: how demographics are will change the built environment

Robert Engelman, vice-president for programmes at the Worldwatch Institute and author of ‘More: Population, Nature, and What Women Want’, formerly vice president for research at Population Action International, founding secretary of the Society of Environmental Journalists,  journalist and contributor to scholarly and news media including Nature, The Washington Post, and The Wall Street Journal.

Fred Pearce, author of Peoplequake: Mass migration, ageing nations and the coming population crash, published in February: environment consultant for New Scientist and writes a weekly online column, Greenwash, for the Guardian: regular contributor to international newspapers and journals, and a regular broadcaster and international speaker: other recent books include Confessions of an Eco Sinner, When the Rivers Run Dry, Earth: Then and Now, The Last Generation (on climate change) and Deep Jungle.  

Professor John Guillebaud, Emeritus Professor of Family Planning & Reproductive Health, UCL, Co-Chair Population and Sustainability Network, Chair People & the Planet, consultant for WHO and other international and national bodies, author of seven books and  numerous publications on birth control, reproductive health, population and environmental sustainability.

Aubrey Meyer, Honorary Fellow of the RIBA, director and founder of the think-tank Global Commons Institute, chief architect of a policy framework for international co-operation on climate change called ‘Contraction and Convergence’, award winning campaigner for an equitable policy for global carbon emissions - recognition including the Schumacher Award, the City of London Life-time Achievement Award, the UNEP FI Global Roundtable Financial Leadership Award and a nomination in 2008 for a Nobel Peace prize by the UK All Party Climate Change Group.

Rosie Boycott, writer, journalist and Chair person of London Food  - an initiative by Mayor Boris Johnson to attempt to help improve Londoners’ access to healthy, locally produced and affordable food: formerly co founder of the feminist magazine Spare Rib, editor of the men’s magazine Esquire, first female editor of two national broadsheets, the Independent, and the Independent on Sunday, and editor of the Daily Express.

Carolyn Steel, architect, lecturer and writer, director of Cullum and Nightingale Architects,  regular columnist for Building Design: author of ‘Hungry City: How Food Shapes Our Lives’, which won the Royal Society of Literature Jerwood Award for Non-Fiction, and was one of the books of the year on BBC Radio 4s The Food Programme.

Jeremy Iles, CEO, Federation of City Farms and Community Gardens, advisor to the Urban Green Space task force, Allotments Regeneration Initiative and the Community Sector Coalition, and Chair of Local Food - £50m Award Partner with the Big Lottery Fund.

John Picard, founding member of the US Green Building Council, member of President Clinton’s ‘Greening of the White House’ team, environmental advisor to several international corporations including Gap, Sony, Siemens, Ford, BP and Interface, sustainability consultant for the city of Greensburgh

Dame Joan Bakewell, broadcaster, writer and Government appointed voice for older people, presenter of a wide range of programmes, including Granada's consumer affairs show Reports Action and BBC's Heart of The Matter: commentator on age issues in her column in the Times and has author of numerous books, including The View from Here: Life at Seventy.

Dan Cruickshank, Architectural Historian, an Honorary Fellow of the RIBA, member of the Executive Committee of the Georgian Group, member of the Architectural Panel of the National Trust, writer of a variety of professional publications, a contributing editor to Architects’ Journal, The Architectural Review and Perspectives on Architecture, and presenter of a host of architectural programmes including ‘Around the World in 80Treasures’ and most recently ‘Dan Cruickshank’s  Adventures in Architecture’.

Sir Richard MacCormac, Chairman MJP Architects, contributor to the Housing our Ageing Population Panel for Innovation (HAPPI) report,  Fellow of the Royal Society of Arts and a Royal Academician, chairman of the Royal Academy Forum, former RIBA President, member of the Royal Fine Art Commission.

Professor Sara Arber, Professor of Sociology University of Surrey, Co-Director of the Centre for Research on Ageing and Gender, Vice President British Sociological Association, President of the International Sociological Association Research Committee on Sociology of Ageing, formerly Vice President of the European Sociological Association, elected Academician of the Social Sciences, and a Fellow of the British Academy.