Over the years, as people have moved out of the very towns and cities they were in the process of populating in 1831, the electoral geography has become heavily tilted against the Tories. On average, Labour constituencies have fewer electors than Conservative constituencies because boundary changes failed to keep up with the migration into the suburbs and countryside. The Coalition agreed in 2010 that rather than a 10 per cent reduction, the Commons should be shrunk to 600 and the number of voters in each constituency equalised at around 75,000 based on the 2015 electoral register. However, although the legislation went through parliament, the Lib Dems refused to let it apply at the last general election.