Revealed: the numbers that show London is too expensive for families How do Britons move around the country as they get older? More specifically, how do they move in and out of the capital as their lives progress? The answer is contained in data newly released by the ONS, which shows radical patterns of migration between London and the rest of the country as our lives progress. Predictably, the largest flight from the city is of young Londoners at 18 - which the ONS puts down to them heading off to university or joining the Armed Forces. But then, at 21, there is a huge net influx of people, as university leavers head to London. The age that accounts for the greatest net influx is when people are 24. But what happens then? What happens is that they get jobs, meet someone else, settle down, maybe get married and start families. The data on the age of women when they have children is here. It shows (countrywide) that the majority of children are now born to women over 29. So he we have two sets of data. One shows that after 30 people start leaving London in ever greater numbers. That exodus hits its peak when men are 36 and women are 35. The other shows that lots of people start families at that age. Curiously the median age at which mothers have a second child is now 30.1 years, (again countrywide) - precisely the age at which people start leaving London. So, is it reasonable to presume that the principal reason people leave London from the age of 30 is that they are starting a family? Is it reasonable to assume that the reason they leave is they can't afford the space in London? Is it reasonable to suggest that, effectively, the soaring cost of property in London is driving out families? Sadly, the answer to all three questions must be "yes."