Over the last decade the number of people aged 65 and over in the U.K. has grown by 6 per cent, from 9.2 million in 1997 to 9.8 million in 2007. Over the next 10 years this older population is projected to grow by a further 23 per cent to 12.1 million by 2017. This is primarily a result of falls in fertility and mortality rates over the past 150 years and changing sizes of past birth cohorts. Population age structures differ by region and local area. In the U.K., the majority of local areas are ageing but a small number are becoming less aged. Information on changes in the size and composition of the older population in local areas is of increasing importance to local government as this group is more likely to be in receipt of health and social services. This article explores changes in population age structure at the Local Authority (LA) level for the whole of the U.K. between 1997 and 2017, focusing on change in the older population.