[holding answer 10 November 2008]: The information requested falls within the responsibility of the UK Statistics Authority. I have asked the authority to reply.Letter from Karen Dunnell, dated November 2008:"As National Statistician I have been asked to reply to your question asking what the most recent forecast is of the proportion of population growth (a) directly attributable and (b) indirectly attributable to migration in each of its projections of population size (234137).""The most recent national population projections, based on mid-2006 population estimates, were published by the Office for National Statistics on 23 October 2007. The principal projection was produced using the main assumptions of future levels of fertility, mortality and migration. However, to give users of the projections an indication of the effect of higher or lower assumptions, a number of variant population projections were also produced.""An understanding of the overall effect of migration on population growth can be obtained by comparing the results of the principal and high and low migration variant projections with those of the 'natural change' (or zero migration) variant projection. Table A below gives projected components of population change for the UK in the period to 2031 in the principal projection, the high and low migration variants and the natural change variant projection.""Table B shows how the projected population growth to 2031 is broken down between the assumed level of net migration and projected natural change. Natural change is then further broken down into that projected in the absence of migration and the additional natural change from the assumed level of net migration. So, taking the principal projection for example, some 47 per cent of population growth is therefore directly attributable to the assumed number of net migrants. The remaining 53 per cent is attributable to projected natural increase (of which 31 per cent would occur in the absence of net migration and 23 per cent arises from the effect of net migration on natural change). In total, therefore, some 69 per cent of population growth in the period to 2031 in the principal projection is attributable, directly or indirectly, to future net migration.""Projected population figures are unchanged since my previous response to PQ 169089 (3 December 2007) concerning the same subject." Table A: Projected population change, United Kingdom 2006-31 Thousand High migration variant Principal projection Low migration variant Zero migration variant Population at mid-2006 60,587 60,587 60,587 60,587 Population change (2006-31) Births 20,305 19,847 19,390 17,458 Deaths 14,291 14,247 14,202 14,244 Natural change 6,014 5,601 5,188 3,214 Net migration 6,382 4,912 3,442 0 Total change 12,396 10,513 8,630 3,214 Population at mid-2031 72,983 71,100 69,217 63,801 Table B: Projected population growth by component, United Kingdom, 2006-31 High migration variant Principal projection Low migration variant Total population increase between 2006 and 2031 (Thousand) 12,396 10,513 8,630 Resulting from: Assumed net migration 6,382 4,912 3,442 Natural change assuming no migration 3,214 3,214 3,214 Additional natural change from assumed level of net migration 2,800 2,387 1,974 Percentage of population growth 2006-31 resulting from: Assumed net migration 51 47 40 Natural change assuming no migration 26 31 37 Additional natural change from assumed level of net migration 23 23 23 Source: Migration and Population. Growth: http://www.gad.gov.uk/Demography_Data/Population/2006/methodology/mignote.asp