Segregation indices measure how social groups are distributed across a region and whether they are separated. A local index compares each place to surrounding places, adopting a network model of space. This allows calculating an index value for each place and examining the distribution. Applying this to London secondary schools, differences were found between schools' proportions of pupils eligible for free school meals and their competitors. Selecting schools showed the greatest differences. No evidence was found that segregation increased from 2003-2008, possibly because the competitive system remained stable, with average patterns of competition unchanged.