In retrospect, we shouldn’t have wasted that lettuce on Liz Truss. The hapless vegetable, monitored by webcam to see if it would outlast the doomed prime minister, could have fed one of the shoppers now staring at bare shelves, as supermarkets ration salads.

Metropolitan society rarely gives much thought to agriculture. But the shortage of tomatoes and cucumbers is a reminder of the daily battle that farmers fight to coax life from the soil. Energy and fertiliser costs have crippled domestic growers, and the latest shortages are clear evidence that Brexit has left the UK at the back of the queue for Mediterranean veg.

“You can’t rely on everyone else to feed you,” I’m told by Minette Batters, President of the National Farmers’ Union, at whose conference this week farmers booed the minister. Greenhouses which could grow tomatoes have been mothballed, she says, because growers don’t qualify for intensive energy support. Partly as a result, this year’s domestic production of salad ingredients is expected to fall to its lowest since records began in 1985.

Environmentally, it would be good to hunker down and eat what’s in season: apples, cabbage, leeks. But until Brits are happy to eat sprouts and parsnips every day, not just at Christmas, it is probably best to increase the amount of locally grown food, rather than import from further and further away. Yet when farmers are pulling out of producing even eggs and milk — UK egg production is at a 9 year low — something has gone very wrong.

Food is the UK’s largest manufacturing sector. Yet a parliamentary committee has warned that it faces “permanent shrinkage” if the acute labour shortages we saw last year continue. Crops were left to rot without pickers, and farmers had to kill their own pigs because of a shortage of abattoir workers — leaving some deeply distressed. One told me that Romanian butchers who wanted to help were prevented from coming to the UK by language requirements. “I didn’t think pigs spoke English” he said wryly.

Six and a half years since the EU referendum, there is still uncertainty about what farming subsidies will be available, and what visas. The anxiety this has created is one reason why over a third of farmers now have mental health struggles, according to a recent survey. Successive governments dithered over how to replace the Common Agricultural Policy (CAP), leaving farmers unable to plan or invest. The EU basic payments scheme, based on land area, is being rapidly tapered down, while the UK pivot to paying farmers to protect nature is criticised as overly complex and prescriptive.

Meanwhile, the government has increased the pressure by signing free trade deals which remove tariffs on cheap food imports with lower standards of production. Farmers, who stand to lose out from the deals with Australia and New Zealand on wine, beef and sheepmeat, were further spooked by the announcement this week that a forthcoming UK-Mexico trade deal will include beef. Many are in despair.

It’s no surprise that governments are in hock to cheap food, especially during a cost of living crisis. But it is an own goal for domestic food production to be plummeting when Covid supply chain problems and the war in Ukraine have emphasised the importance of food security. Farmers can’t keep selling for less than it costs them to produce.

These issues rarely come up in urban conversation. Agriculture is regarded with the same kind of disdain applied to religion. Hipsters who care about food miles and animal welfare, and interrogate ingredients labels for additives, are quite likely to shrug at the plight of farmers, citing their support for Brexit. In fact, analysis suggests that around 53 per cent of farmers probably voted Leave, against a national average of 52 per cent, with the National Farmers’ Union campaigning for Remain. The idea of farmers for Brexit may be an urban myth. And in any case, we don’t stop caring about the motor industry just because some Sunderland car workers voted Leave.

It’s not just Remainers who shrug over the fate of our farmers; the Brexiters do too. They disliked the rewards reaped by French agriculture from the bloated CAP, but never worked out what to do with an industry which is by its nature heavily subsidised — and heavily regulated. Historically, it was assumed that Conservatives had some affinity to the land. But knowledge of the countryside seems to have dwindled. Tenant farmers, for example, manage roughly a third of all farmed land in England, sometimes on very short tenancies. But the government has still not responded to a review it commissioned a year ago, which argued for greater protection because tenant farmers were “especially vulnerable to the policy changes being enacted by the government”.

Given all this, it’s not surprising that the Conservatives are losing the rural vote. The by-elections in North Shropshire and Tiverton and Honiton were a warning sign, with both seats swinging to the Liberal Democrats. Since then, ministers have done little to reassure. While NFU delegates were hostile to environment secretary Thérèse Coffey, Sir Keir Starmer was (politely) applauded. Claiming that farming was in his “DNA”, the Labour leader said that food security matters and pledged that if Labour win, half of all food bought by the public sector will be local. Such a clear bid for the farming vote would once have seemed audacious; it’s now eminently sensible. In a temperate climate well suited to agriculture, environmental policy and food security should go hand-in-hand. But we need a government that actually cares about it.

camilla.cavendish@ft.com