Alarm over migration is at highest level ever: Half of Britons say it’s one of most important issues facing the country

Concern about mass immigration is now at the highest level ever recorded, ministers have been warned.

For the first time, half the public say controlling Britain’s borders is among the most important issues facing the country.

The figure has surged by eight percentage points in a single month amid the crisis at Calais, during which thousands of illegal immigrants have laid siege to the Channel Tunnel.