The number of local authorities where more than a quarter of the population are aged 65 and over is projected to increase from an estimated 24 areas in mid-2012 to 83 areas in mid-2022.
The increase was by far the highest of the three age groups in the projections, with children aged up to 15 at only 9.2% in comparison.
The organisation said this was a result of the general ageing of the population as forecasted in the national population projections.
The fastest growth in those aged 65 and over is expected to be seen in the East Midlands where the number is
projected to increase by 25% from 8.1 million to 10.1 million over the 10 year period.
Estimates indicate that in mid-2012 there were 24 local authorities where more than a quarter of residents were aged 65 and over.
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The report, released today, said: "By mid-2022, it is projected that the number with this proportion will have increased more than threefold to 83 local authorities.
"Quantifying these trends is important in order to inform organisations who are interested in the population in this age group.
"For example, projections can be used to inform organisations involved in planning for health and social care
provision, reviewing transport needs and business planning."