The British population rose by 10 million between 1950 and 2000. It is expectected to continue to grow by 6.1 million to 65.7 million by 2031 before reaching its peak of 67 million around two decades later.
The UK population increased by 7.0 per cent since 1971, from 55.9 million. Growth has been faster in more recent years. Between mid-1991 and mid-2003 the population grew by an annual rate of 0.3 per cent.
Birth rate remains far higher than in southern and central Europe, with an average of 1.7 children born to each British woman.
There were 695,600 live births in the United Kingdom in 2003, a live birth rate of 11.7 per 1,000 population. Projections suggest that the number will remain relatively constant at around 680,000 over the next 40 years.
Rising immigration is the main reason for Britain's increasing population.
Figures released by the Office of National Statistics (ONS) in the UK show an increase of 185 000 in Britain's population due to immigration, for the year 2005. This is an increase of 500 people a day.
565 000 migrants arrived in the UK in 2005, intending to stay for at least a year. At the same time about 380 000 people left the UK to live abroad, over half of them British citizens.
The inflow from migrants to the UK was the second highest total recorded since 1991 and was fuelled by the inclusion of new member states to the EU in April 2004. The largest single inflow from migrants came from Poland with 57 000 arriving in 2005.