Emergency plans are being drawn up to evacuate the Queen, the Duke of Edinburgh, Prince Charles, Prince William and other senior royals out of London to safer secret locations in the country in case there is a total breakdown in law and order and riots break out after a no-deal Brexit.

According to reports in the Sunday Times and other newspapers that have not been denied, a cabinet office source explained: “These emergency evacuation plans have been in existence since the Cold War but have now been ‘repurposed’ in the event of civil disorder following a no-deal Brexit.”

There are discussions taking place between Scotland Yard and at least one regional police force.

“This is a measure extremely unlikely to come to pass but the powers that be need to have contingency plans for any eventuality,” said a government source, who added: “The decision to evacuate members of the royal family is based on whether or not their safety is compromised. But right now we have no concerns about their safety.”

Fears are mounting over a no-deal Brexit. A source in the planning secretariat said the most extreme no-deal crisis scenario envisaged riots breaking out in London as shops ran short of staple foods.

Originally named Operation Candid, plans were drawn up for the Queen to be evacuated to sea on the royal yacht Britannia if the Soviet Union launched a nuclear attack.

After the royal yacht was mothballed in 1997, the plans were amended to include evacuation via the Hebridean Princess, a cruise ship that would have ferried the royals around the remote Scottish Islands in the event of disaster.

The plans, first devised in 1962 after the Cuban missile crisis and approved the following year , have now been revised by senior civil servants involved in contingency planning for Operation Yellowhammer, the battle plans for what happens in the event of a no-deal or no Brexit.

Officials in the civil contingencies secretariat, the government department responsible for emergency planning, have “repurposed” the secret operation under which the royals could have been accommodated in various country houses to protect them from enemy forces during the Cold War.

There have been growing concerns that the Queen’s position was being “dangerously politicised” and she was being dragged into the Brexit debate.

Senior Whitehall officials fear the Queen, who must remain neutral, could become the target of public anger.