Spanish families, an Australian podiatrist, a Lithuanian cook and his partner: Newcomers from London who have turned their backs on the city to return home have been everywhere for months.

A recent study by the Economic Statistics Center of Excellence, a think tank for economic statistics, suggests that these observations are more than the usual comings and goings in a metropolis with a population of millions. According to the calculations of the authors Michael O'Connor and Jonathan Portes, 700,000 foreigners could have left the city in the past twelve months.