Almost 250,000 people fled London for other areas of the UK prior to the coronavirus lockdown, research has shown.
Analysis carried out by the University of Oxford shows that thousands of city-dwellers relocated to less populous parts of Britain before the lockdown began on March 23.
Data collected from smartphone apps by advertising company Cuebiq was analysed for the study.
The majority went to the east of England and southeast, according to the research, with the mass exodus beggining in early March.
Communities in second-home hotspots have pleaded with people to stay away since the lockdown began last month.
Police in Devon and Cornwall, Wales and Norfolk have been battling to enforce the strict restrictions on movement imposed by the government.
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The Oxford University data 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.
It also shows that vast numbers of people left London in the days immediately after the lockdown, although less attempted to get away than in the preceding two weeks.
More than 50 per cent of those leaving went to the east of England, and 25 per cent went to the south east.
Data for people leaving Manchester and Birmingham showed thousands of people left Manchester for London before the restrictions.
After the lockdown more than 30,000 have travelled to the city from Yorkshire or the rest of the north west.
Over 200,000 people reportedly left Birmingham bound for the rest of the west Midlands.
Dr Adam Saunders, co-leader of the Oxford Covid Impact Monitor project said: "We're confident that the results which have been provided are representative of terminal outflows from London or an 'exodus' effect during the period shown when compared to pre-crisis mobility patterns."