More than 4,000 sheep are transported to Europe for slaughter each year

Plans for the mass slaughter of sheep mid-transit are being discussed by Whitehall officials should ports be closed in the event of a no-deal Brexit.

Sensitive discussions about what to do with livestock if there are days of delays or closures at ports such as Dover are under way in No 10 and government departments.

Mandarins are considering extreme contingency scenarios, which they know are likely to be dismissed as “project fear” by some MPs and members of the public. Nevertheless they also worry that failure to plan for certain outcomes, however unlikely, would lead to significant criticism if they were found to have underestimated the scale of the challenge.

Makers of cars and some medical goods have received significant attention for their reliance