The information requested falls within the responsibility of the UK Statistics Authority. I have asked the authority to reply.
Letter from Stephen Penneck, dated March 2010:
As Director General for the Office for National Statistics, I have been asked to reply to your recent Parliamentary Question asking how many people and what proportion of the total population in each local authority area are projected to be over 65 years old in (a) 2015, (b) 2020, (c) 2025, (d) 2030 and (e) 2050. 
The table shows the projected population aged over 65 years in each local authority in 2015, 2020, 2025 and 2030. These are 2006-based Subnational Population Projections which were published by the Office for National Statistics on 12 June 2008. The Office for National Statistics has not published population projections at local authority area for 2050.
A copy of the table has been placed in the House of Commons Library.
The subnational population projections are demographic trend-based projections that indicate what the population of an area is likely to be if recently observed trends in fertility, mortality and migration were to continue. They take no account of future policies or developments which may affect trends.
The 2008-based Subnational Population Projections are due to be published on 27 May 2010.