United Kingdom population trends in the 21st century.

This article considers the likely trends in population size, age structure and potential support ratios in the United Kingdom over the coming century. The extent to which these trends could be modified by changes in fertility or migration levels is examined. The findings of a recent United Nations report on 'Replacement Migration' are also considered in the light of the Government Actuary's official population projections for the United Kingdom' together with new projection scenarios prepared specially for this article.