The economy could “easily” contract in the coming weeks by as much as it did in more than a year during the financial crisis, a senior forecaster has warned.

As ministers were being urged to do more to help businesses survive the coronavirus, Julian Jessop, an independent economist, said a 6pc drop in GDP or “even worse” in just one quarter can be expected.

Mr Jessop said his rough calculations, based on estimates that one in five Britons will be unable to work in the coming weeks and policy countermeasures such as last week’s interest rate cut, mean 2020 will be a “write-off” for the economy.

He warned that a plague of bankruptcies of previously healthy companies would make a “swoosh-shaped” recovery in 2021 more difficult.

This weekend there are signs that thousands of companies and millions of jobs are already at risk. Shops, hotels and restaurants face an immediate cash crunch as consumers stay at home.