<b><b><b><b></b></b> Housing affordability indicators are warning of possible trouble ahead - particularly for London and the south east. <b><b><b><b>John Stewart</b></b></b></b> looks at the numbers </b></b><br><b><b></b></b><br> Housing and planning did not register among voters' concerns in the general election, despite the affordability problems faced by many home buyers in southern England. But the chancellor - and Britain's housebuilders - would be wise to keep a watchful eye on the housing market. If interest rates have to rise, as seems increasingly likely, and if house prices continue to increase at their current rate, then the housing market could be in for some turbulent times over the next two years. <p></p><p><b><b>A warning signal</b></b><br> The housing affordability index* compiled for<i> Housing Market Report</i> and Cheltenham &amp;&amp; Gloucester stood at 32.8 in the first quarter of 2001, just above its long-term average of 32.4 (see chart below). This benign situation is heavily dependent on today's historically low interest rates. </p><p>Stripping out interest rates from the index, we are left with the house price/earnings ratio. </p><p>Using Nationwide house prices, the UK house price/earnings ratio for a single male on average earnings was 3.3 in the first quarter of 2001, well below the 4.7 it reached in …