Agriculture & Horticulture Development Board chairman John Bridge spoke of a "perfect storm" of coincidences, such as climate change and economic turmoil, that made managing food security more difficult.
"We can't take food security for granted. We are on the edge of a new population food paradigm. For 60 years supply kept up with, or ahead of, population growth, but that relationship will be reversed."
He was speaking at the launch of Feeding Britain, a report by industry leaders for the Smith Institute think-tank. The document highlighted "distinct opportunities" to increase fruit and vegetable production in the next 20 to 30 years.
Council of Food Policy Advisers chairman Dame Suzi Leather told the conference: "We are haunted by the spectre of the Common Agricultural Policy, and overproduction has been appalling. But, looked at through the lens of food security, we should be very concerned about some of our production levels. Only 10 per cent of our fruit is produced nationally and that is a disgrace."
Shadow environment secretary Nick Herbert said: "Nudging the pendulum back towards domestic production is not the same thing as 100 per cent self-sufficiency. But it will help to improve our resilience.
"It's not about central targets or ushering in re-intensification of agriculture. But increasing our productive capacity can't be about retreating to protectionism: we need more trade, not less.
"Trade liberalisation will affect producers, but the current approach - expecting farmers to operate in a free market but hampering their ability to compete - is an untenable half-way house.
"Rules need to be based on outcomes and processes, he said. They needed to encourage a fairer relationship between suppliers and supermarkets, and guard against domination by monopolies."