IN THE UNITED KINGDOM?
The Westminster Parliament has traditionally been dominated by the two-party system, with two main parties forming the Government and Official Opposition. Over the years these have been Whigs and Tories, Liberals and Conservatives and, since the development of the Labour party since the beginning of the twentieth century, Labour and Conservatives. A number of other smaller parties and, occasionally independent candidates, also win seats in Parliament.
Major parties
The Conservative Party, centre-right to right-wing (traditionally right-wing) 
The Labour Party, centre-left to centre (traditionally centre-left)
Co-operative Party (all Co-operative Party MPs are also Labour MPs as part of a long-standing electoral agreement)
Liberal Democrats, centre-left (traditionally centrist)
