Salisbury, Sunderland and Carlisle are among the English cities where jobs would be worst hit in the event of a no-deal Brexit, according to a secret government list leaked to The Sunday Times.

The document, marked “official sensitive” — requiring security clearance on a “need to know” basis — reveals that 29 of the 33 areas most vulnerable to job losses if the UK crashes out of the European Union voted leave.

It is this kind of information that has put pressure on the prime minister, Boris Johnson, to move away from the idea of leaving the EU without a deal.

The list, which was compiled under the codename Operation Kingfisher, the government’s contingency plans to prop up businesses, was created in the run-up to