4.5million flee crowds of London and the South East to move to the coast or the country

Many were families who used the profit they made on their houses to move to the coast or the country. Villages in the South West of England proved particularly attractive.

The leavers were replaced by a larger number of migrants from other parts of the UK and overseas, mainly young single people chasing work, giving the region a net population gain of 384,000.

The figures, compiled from official sources by the Halifax, also point to a change to the ethnic mix of major urban centres, where minority communities make up a growing proportion of the population.

Birmingham, for example, saw a net fall in its British origin population of 61,000 over the ten-year period. Some analysts predict that next year the city, which has a large Asian community, will be the first in the UK that no longer has a majority white population.

The figures show 2.4million people left London between 1996 and 2006. A further 2.1million moved out of the South East.

While the capital has long been a magnet for young people from other parts of the UK, in recent years these incomers have failed to make up for the exodus of Londoners. As a result, London's "British" population fell by 608,000, which was the greatest net loss seen in any part of the country.

However the loss was more than offset by the arrival of a million people in the capital from overseas over the past decade.

Many have come from Eastern Europe, particularly Poland, following the expansion of the European Union.

London's total population has increased by 538,000 since 1996, which was the biggest increase seen by any part of the country.

Coastal areas overall have seen the biggest increases in net internal migration. The South West saw a net increase of 441,000 in the population since 1996, far more than any other part of the country.

Halifax chief economist, Martin Ellis, said: "Sixteen of the 20 local authorities with the highest levels of net internal migration since 1997 are coastal areas. People are moving in large numbers to enjoy the benefits of living near the sea."

In rural Britain, the East Riding of Yorkshire recorded the biggest net gain from internal migration. Some 112,000 arrived compared with the 87,000 who left - a net increase of 25,300.

Only the cities of the North East of England, including Newcastle, Sunderland and Middlesbrough, saw an overall population decline between 1996 and 2006.

The figure fell by 20,000 as young people moved away in search of work and a new life.

Figures published by the Office of National Statistics earlier this week reveal that England is about to become the most crowded country in Europe.

They show that in England in 2005 there were 387 people for every square kilometre, and this rose to 390 per square kilometre in 2006. This is around 620 per mile.

The population densityin England is almost double that of Germany and four times the figure of France.

Mr Ellis said: "The figures do show a flight from cities and urban centres to more rural locations and the seaside. Many will be people with children who are looking for a more family-friendly quality of life.

"We don't have a demographic breakdown as to who is going, but it will include a number of middle-aged and older people who have made money from the property market.

"They will be looking to buy a larger property outside London, some will aim to move to an area where they can live mortgage free.

"There is a natural life- cycle going on. Young single people will gravitate towards cities, but as people marry and have children they look for larger homes and space."