What does 'food security' actually mean?

'Food security' is suddenly on the agenda - but what is it?  Was it ever about calories & cheap food for the masses?  And if it was, isn't it time that we redefined food security for the modern world - recognising the essential role that land use, food system resilience, and nutrition play in ensuring that all citizens can eat, and eat well. This programme features Vicki Hird from Sustain, Professor Tim Benton from Chatham House, and Patrick Holden from the Sustainable Food Trust. Produced by Farmwel.