"What would be the impact if every garden in London grew carrots?"
The audience chuckled. David, the guy earnestly posing the question, looked peeved. David's question was serious but the South Bank audience couldn't resist the thought of thousands of Londoners chomping carrots - Bugs Bunny-style - at bus stops, on the tube and down the pub.
Professor Jayati Ghosh, a key player in the nef debate, answered David. Urban agriculture in Cuba, she explained, had switched in recent years from large state-owned mono-crop farms to a system of polycrop smallholdings where citizens grow food for their families, neighbourhoods and for sale at markets.
I'd heard about this Cuban transition a few days earlier at a smaller gathering at the Marchmont Street Community Centre near Russell Square. Cuban agro-ecology scientist Fernando Gunes-Monzote explained how a land redistribution programme started a few years ago had encouraged 100,000 people - many of them young people living in towns and cities - to farm their own land.
Fernando showed recent photos of these Cuban smallholdings. One showed a strip of land, not much longer and no wider than the average back garden of a London semi, full of flourishing crops - pineapples, yams, cassava, tomatoes and bananas.
Locally organised organic urban farming now supplies the people of Havana and other towns with 80% of their food.
I began to wonder - what would be the impact if 100,000 people in London started growing their own fruit and vegetables?
Where did our money go? Surviving and thriving in the Great Transition, Wednesday, 27 October 2010, hosted by nef.
Image: Imperial War Museum
Paul Coleman, London, October 2010.