Current UK population (June 2016) is 65.1m of which 17.8% (11.6m) are over 65.
Cannot find the 65.1m figure broken down by age bands, but a 2012 report forecast the likely breakdown as follows: age 0-15 = 11,497m, age 15-29 = 12,619m, age 30-44 = 12,545m, age 45-59 = 13,018m, age 60-74 = 9,709m and age 75 and over = 5,388m.
Scottish mid-2015 estimates were: age 0-15 = 17%, age 16-64 = 65% and aged over 65 = 18%.
In 2010, 65% of benefits (including state pension) went to those over working age. The average NHS spending on the elderly is nearly double that for working people. The most elderly (over 85) cost 3 times the amount that goes to those aged 65-74.
This skewing of the population to the elderly section of the population is due to the baby boom experienced after WW2 and through the 1960s, and the advances in medical care raising their life expectancy.
In addition to the burden of benefit payments and use of the health service, they disproportionately influence politics and voting being traditionally conservative in their views.
Various sources
