The proportion is expected to grow in all regions, with London’s plus-65 population projected to grow fastest, with an increase of almost 24.8% over the 10-year period from 1.02 million to 1.27 million by mid-2026.
The number of people aged 65 and over is also projected to increase for every local authority in England in the 10 years to mid-2026.
Over the same period, the proportion of people in the age group is forecast to go up in all but five local authorities – Bexley, Brentwood, City of Bristol, Coventry and Havering.
In those areas the population growth rate is projected to be faster for those aged under 65 years.
In mid-2016, 36 local authorities in England had a population where at least one-quarter of people were estimated to be aged 65 and over.
The old age dependency ratio (OADR) of an area can change as a consequence of an ageing population.
OADR is defined as the proportion of people of state pension age relative to the working age population, expressed as the proportion of dependants per 1,000 working age people.
Under current legislation, the state pension age will gradually rise to 67 by 2028.
The South West was the region with the highest OADR in both mid-2016 and mid-2026, at 379 and 383 respectively.
The lowest OADR was seen in London, with 183 in mid-2016 and 182 by mid-2026.
In the longer-term, OADRs are projected to increase in every English region by mid-2041 as the 1960s ‘baby boomers’ reach state pension age from the late 2020s and life expectancy continues to improve.
Andrew Nash, of the ONS population projections unit, said: The population is ageing in all regions, with the number of people aged 65 and over growing considerably faster than younger age groups.”