A study has found that an increase in “diversity” makes existing residents of an area feel unhappier and more socially isolated, while those leaving for more homogenous areas populated by their own ethic group often get happier. Among the reasons for residents feeling insecure as their area diversifies, is that people tend to spend time with those they perceive as like them, and feel less secure when experiencing rapid change, the authors explained. Already around a fifth of people in the UK are non-white or non-British. This is expected to rise to a quarter by 2025, a third by 2040, and could reach up to 38 per cent by 2050. The large- scale sociological study, undertaken by the Cathie Marsh Institute for Social Research at the University of Manchester, drew on 18 years of data of more than 10,000 people.