United Kingdom has a system of parliamentary uninominal. This prevents forces that draw less than 30% at the national level have a significant representation in the House of Commons and to this always there are only two major parties alternating in power (labour and conservatives). The labour left has tended to defend this system and oppose establishing proportional representation because they see labour with 35% of the votes managed to get 55% of the Parliament. However, this model prevented this have an own electoral profile and constantly obliges you always head down to the right of his party under the threat that Yes is not subjected to address labour could split up and allow conservatives to explosions in the elections. This system although today reduced the number of seats for the Conservatives, works in favour of these because it neutralizes to those who want to capitalize on discontent with this Government by the left and makes Brown wear be channelled through them.