Jay Rayner tells us in The Observer that:

There is an imperative for Britain to become more self-sufficient, not for reasons of petty nationalism or to fulfil some agrarian fantasy of localism but because, without it, in the current political climate, we risk not being able to keep ourselves fed. There are a number of levers that can be pulled.

So therefore we must all pay more for Good British Food so that Good British Farmers can supply us in our greater self-sufficiency.

Also in The Observer, on the same day, a story about that other current green obsession, electric cars and the minerals with which to make their batteries:

Macquarie Research predicts that trouble in the DRC and rising demand for electric vehicles will lead to a four-year-long cobalt shortage. Writing in academic journal The Conversation, Ben McLellan, senior research fellow at Kyoto University, warned further: “Manufacturers such as electric vehicle makers should be concerned that the supply of one of the key mineral components, or the processing and refining infrastructure, could become too centralised in a single country. Without diverse source options, the possibility of supply restriction becomes more likely.”

It is of course the second of these ideas which is correct. Security of supply comes from having many sources of supply each enjoying, or suffering from, different sets of conditions. With minerals the thing to worry about is some feckless incompetent gaining political power and thus disrupting supply. With agricultural production that too matters - Zimbabwe is no longer the major maize exporter it once was - but we also have natural variability of weather. We want to be sourcing our food from as many different "weather areas" as we can.

Earlier in the year there was a lettuce shortage in the UK as Spanish weather disrupted the crop. Not a huge problem as other more expensive sativa could be supplied from elsewhere. But imagine the problems Spain would have had if they were attempting to produce all the food consumed there purely there? 

This is not idle speculation either. The last incidences of true swollen belly children falling down dead famine in England were in Nothumberland and Cumbria just before the railway networks reached there. The reliance upon local food when the crop failed kills in the absence of the ability to acquire food elsewhere.

We agree entirely that security of supply of food is an excellent idea, as it is with minerals. But the solution with food is also as it is with minerals - many widely dispersed, subject to different conditions sources of supply. Self-sufficiency is the direct opposite of secure.