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Lockdown measures have been in place across Europe since mid-March to contain the pandemic, leading to the closure of many businesses and limiting people's movements.
Last month, sales to businesses accounted for four in five of the 4,321 registrations, according to the data from the Society of Motor Manufacturers and Traders (SMMT), which downgraded its full-year forecast to 1.68 million sales, on course for the lowest level in nearly 30 years.
"The market’s worst performance in living memory is hardly surprising," said SMMT Chief Executive Mike Hawes.
"Safely restarting this most critical sector and revitalizing what will, inevitably, be subdued demand will be key to unlocking manufacturing and accelerating the UK’s economic regeneration."
In February 1946, just a few months after the end of World War Two, just 4,044 new cars were sold in Britain, which was still undergoing rationing and trying to rebuild after wartime destruction, under its first majority Labour government.
(Reporting by Costas Pitas; editing by Stephen Addison/Guy Faulconbridge)