The existence in Britain of organized political parties each laying its own policies before the electorate has led to well-developed political divisions in Parliament. The party system has existed in one form or another since the seventeenth century, and began to assume its modern shape towards the end of the nineteenth century. Whenever there is a general election (or a by-election) the parties may put up candidates for election. The electorate then indicates, by its choice of candidate at the poll on election day, which of the opposing policies it would like to see put into effect. The candidate who polls the most votes is elected: an absolute majority is not required. Such an electoral system is called the majority system, which is unrepresentative and undemocratic because it gives predominance to the most powerful parties — the Conservative and Labour parties. These parties as a rule control Parliament. In this context there is a two-party system in Britain. The Conservative and Labour parties share power, they control the state mechanism, only these two parties have access to the management of the state, though in reality there exist other parties.

However, in recent years new trends are becoming more noticeable. These changes which occurred under the pressure of the working people, disappointed with the existing state mechanism, make it more complicated for the two main parties to dominate the political scene. A reflection of the tendency is the fact that more votes are given to the other political parties.

The modern party system in Britain is a result of the Industrial Revolution which took place in the eighteenth and early nineteenth centuries, the emergence of new classes on the political scene — the capitalists and working class, the organized political struggle of the working class. The Industrial Revolution brought into being the industrial proletariat and with it the fight for civil and political rights, trade-union organization and the right to vote. Under such conditions the ruling-classes found it necessary to create political organizations which were intended to defend their class interests. This in its turn led to the emergence of the Conservative and Liberal parties in the nineteenth century as parties of the propertied classes.

By the end of the nineteenth century, both major political parties had become organized on a nationwide basis with election agents, constituency organizations and a London headquarters. In Parliament, the two-party system which had been emerging from the end of the eighteenth century was given formal acknowledgement when the House of Commons was rebuilt after a fire destroyed the old one in 1834. A new chamber was provided with two sets of benches, one for an administration party, one for an opposition party. Political struggle led to the formation of the Labour party in 1900 and to the foundation of the Communist party in 1920.