The number of people aged 65 and over is predicted to rise by nearly two thirds in the UK to reach 15.8 million by 2031, according to figures released today.
More than one in five of the UK population - 22% - will be 65 and over by 2031, with Northern Ireland, the East Midlands and the East projected to have the highest increases in this age group and London predicted to have the lowest.
People aged 50 years and over already made up at least one quarter of the population in each region and country in the UK in 2008 with the highest percentages found in the South West - at 39% - and Wales at 37%, the Office for National Statistics (ONS) figures show.
The region with the largest population aged 50 and over was the South East at 2.9 million - or 35% of the population.
London and Northern Ireland had the lowest percentages of people aged 50 and over at 26% and 31% respectively.
A net figure of almost 25,000 people aged 50 years and over left London between mid 2007 and mid 2008.
The South West, the East, the South East, the East Midlands and Wales were the biggest beneficiaries of the "internal migration" of over 50s, according to the figures for the English regions and Wales.
The exodus of over 50s from London was the highest by far, ten times that of the next highest region, the North West, where 3,000 people in this age group left during this period.
The capital also had the highest proportions of men and women aged 65 years and older who were single and never married in 2008 compared to other UK regions as well as the highest proportion of divorced and separated people in this age group.
Paul Vickers, deputy head of the centre for regional and local statistics for the ONS, said: "London has the highest proportion of single men and women aged 65 years and over, so sort of indicating that the migration itself might be among married couples who are prepared to migrate together whereas single people probably want to stay put."
The figures also showed the economic wellbeing of older people varied according to region.
Employment rates for those aged 50 to state pension age in 2008 were at the highest in the South East and lowest in Northern Ireland in 2008.
In 2008, around a quarter of the British population aged 60 years and over were either claiming pension credit or benefiting from it by being related to someone who did claim, the figures showed.
The North East had the highest percentage of the over-60 population - at 33% - receiving this benefit while the South East had the lowest at 18%.
London had the highest percentage of people aged 60 and over living in low income households between 2005/6 and 2007/8 at 22% followed by the East Midlands and Northern Ireland.
The figures also showed the impact of an ageing population on the regions.
There were 173 hip and knee replacement procedures per 10,000 people aged 65 years and older living in the South West region in 2008/9, according to the report, the highest rate amongst the English strategic health authorities compared to London where the figure was 118.Reuse content