1. First Past the Post (fptp)

FPTP is the current system for electing MPs to the House of Commons. It is a plurality system with 646 separate constituencies each electing a single Member of Parliament. Winning candidates simply need to gain more votes than any other candidate; this need not be an absolute majority of all the votes cast in a constituency. FPTP is also used for local elections in England and Wales.

2.Supplementary Vote (sv)

voters are limited to indicating a first and second preference. There are two columns on the ballot paper and voters can mark an X in the first column for their first choice candidate and another X in the second column for their second choice. (Voters are not required to make a second choice if they do not wish to.) A candidate who receives more than 50% of the first preference votes on the first count is elected. The system is used to elect the Mayor of London.

3.Single Transferable Vote (stv)

Voters rank the candidates on the ballot paper by marking 1, 2, 3 etc against the candidates’ names. Voters can rank candidates both within parties and across different parties. Winning candidates must obtain a certain quota of votes in order to be elected. The system is used for local government elections in Northern Ireland and Scotland, European Parliament elections in Northern Ireland and the Northern Ireland Assembly.

4.Additional Member System (ams)

voters cast two separate votes, the first for a constituency MP and the second for a party list. A proportion of the seats are elected by the First Past the Post System and the rest are regional list Members elected for each region from closed party lists. AMS is used for elections to the Scottish Parliament, the National Assembly for Wales and the London Assembly.

5.Closed Party List System

has been used for European Parliament elections in the UK since 1999 except in Northern Ireland where STV is used. Under the system electors vote for a party in a multi-member constituency; each party receives seats in the constituency in the same proportion as the votes it won in that constituency.

The system of political parties in the UK appeared in the 17th century. At first, there were two parties - Tory (the party that supported the King) and Whigs (who supported the Parliament). The word "tory" means "an Irish robber". A "whig" was a Scottish preacher who could preach moralising sermons for several hours.

Now the main British political parties are:

the Conservative Party

the Labour Party

the Party of Liberal Democrats

Since 1945 the British Government is constantly represented by two political parties: Conservative (who are called "Tory" by their opponents) and Labour (called "Whigs"). In 1988 the Liberal Party made an alliance with Social Democrats and the Party of Liberal Democrats was formed.

The proportional representation system in the UK means that all political parties, small and large, are represented in the government according to the proportion of votes they receive.

Executive power in the United Kingdom is exercised by the Sovereign, Queen Elizabeth II, via Her Majesty's Government and the devolved national authorities - the Scottish Government, the Welsh Assembly Government and the Northern Ireland Executive.

The monarch appoints a Prime Minister (David Cameron) as the head of Her Majesty's Government in the United Kingdom, guided by the strict convention that the Prime Minister should be the member of the House of Commons most likely to be able to form a Government with the support of that House.