Almost 250,000 people left London before the UK coronavirus lockdown came into effect, figures from Oxford University show.

Data shows that thousands flooded out of the capital toward other parts of the country before people were instructed to stay at home on March 23, with the majority going to the east of England and South East.

Local politicians and businesspeople in Norfolk, the South West and Wales had pleaded with wealthy second homeowners not to leave their homes to travel to the regions, fearing that they could bring the virus with them and put extra strain on local health systems.

Residents of beauty spots in Cornwall and west Wales put up signs asking travellers to return home.

The data, which shows cumulative outflows from London from the start of March until mid-April, suggests that people began to leave in large numbers on March 12, with numbers flattening at just under 250,000 after the lockdown less than a fortnight later.

More people left in the days immediately after the lockdown, but movement levels were much lower than during the previous two weeks.

As of Tuesday, more than half of the exodus was to the east of England, while another 25 per cent went to the south east.

Almost 10 per cent of the total outflow was to the East Midlands, while smaller proportions went to Wales, the West Midlands and Yorkshire.

The data was collected from smartphone apps by advertising company Cuebiq and analysed by academics at Oxford University.