The affordability of housing is a major policy issue that has increasingly become a concern for UK government as house prices have risen dramatically in recent years. This is partly because of the importance of affordability for the recruitment and retention of key workers, many of whom are on national pay scales and earning salaries that do not fully reflect the differences in prices that exist, in particular between London and the South East and the rest of Great Britain. Government policy is to increase the supply of housing in order to improve affordability in the greater South East. However, assuming that this expansion in housing supply is also to be accompanied by an expansion in employment, the outcome is that there will be both an increase in supply and in demand for housing, with the counter-intuitive result that, under one of the scenarios set out in this paper, in some areas affordability will worsen rather than improve