The current methodology for determining assumptions of future
migration was introduced for the 1991-based national population
projections.1 With some later modifications,2 this approach,
which standardises the methods and procedures by which the
assumptions are formulated, has been the basis of subsequent
projections. This chapter summarises the assumptions adopted for
the 2010-based population projections. It is important to
emphasise that the migration assumptions are based on past
demographic trends. They do not attempt to predict the impact
that new or future government policies, changing economic
circumstances or other factors (whether in the UK or overseas)
might have on migration patterns. The new long-term assumption
for net migration to the UK is +200,000 each year compared with
+180,000 a year in the 2008-based projections. Figure 5.1
compares the future net migration assumptions with historical
international migration estimates back to 19913 and also
includes the assumptions made for the previous 2