“They have the power to save British bacon for future generations if they check it is British rather than imported when they are shopping,“ said Dr Zoe Davies, who represents the nation’s pig farmers. “Please make an extra special effort over the next few weeks to look for the British Red Tractor logo.“

British pork and bacon has already had an important boost from the London Olympics organising committee, which insists that all pork and bacon served at the Games is Red Tractor accredited.

But so far this week three more pig farmers have announced they are selling their herds because of mounting losses. This means a weekly loss of 63,000 rashers of British bacon, 95,000 sausages and 10,000 pork pies — just from these three farms.

Failing harvests of wheat, maize and soya around the world have caused a shortage of pig feed, driving up the cost of feeding Britain’s pig herds to an unprecedented level.

"If supermarkets see a surge in demand for British product, it will persuade them to pay our farmers the few extra pennies a kilo more they need to cover their soaring feed bills,“ said Zoe Davies, who is general manager of the National Pig Association.

"Shoppers have always been incredibly loyal to British pig farmers in the past so we’re asking them to please be extra careful to look for the British Red Tractor logo on bacon, and also on sausages, and fresh pork.“

Bacon is Britain's favourite food, according to the Top 100 Foods Index — but it is under threat because farmers are losing around 310 on every pig they sell. Unless supermarkets ensure they receive around 10p a kilo more, many will not be able to survive until feed costs return to more normal levels.

According to a National Pig Association survey of members, pig farmers representing ten percent of the nation’s pig supply will have to stop production over the next six months because they cannot afford to feed their pigs — unless retailers, which sell 86 percent of all British bacon, pay them a bit more.