The information requested falls within the responsibility of the UK Statistics Authority. I have asked the Authority to reply.Letter from Karen Dunnell, dated October 2008:"As National Statistician I have been asked to reply to your asking what proportion of projected growth in population she expects will be accounted for by (a) immigration and (b) natural growth at the point at which the domestic population reaches 70 million. (232523)""The most recent national population projections, based on mid-2006 population estimates, were published by the Office for National Statistics on 23 October 2007. Under the principal projection, the population of the UK is expected to reach 70 million in 2028.""Figures on the proportion of projected growth attributable to immigration and natural growth for the year 2031 are available. A table showing these proportions is given below." Projected population growth by component, United Kingdom, 2006-31 Principal projection Total population increase between 2006 and 2031(thousand) 10,513 Resulting from: Assumed net migration (thousand) 4,912 Natural change assuming no migration (thousand) 3,214 Additional natural change from assumed level of net migration (thousand) 2,387 Percentage of population growth 2006-31 resulting from: Assumed net migration 47 Natural change assuming no migration 31 Additional natural change from assumed level of net migration 23 Source: Migration and Population growth: http://www.gad.gov.uk/Demography_Data/Population/2006/methodology/mignote.asp