Elections are dominated by political parties and so political scientists have tried to analyse how parties relate to each other in Party Systems.
Party Systems can be analysed in terms of:-
Many parties contested seats in the 2010 election but some of these such as the English Democrats, the Christian People’s Party and the Monster Raving Loony Party cannot be said to have had much effect on the result.
A significant/effective party needs to get a sizeable proportion of the vote and win a number of seats.
There is no absolute definition of what is significant but UKIP in 2010 with 3.1% of the vote and no seats might not be thought significant, though their intervention may have lost the Conservatives a handful of very closely fought constituencies.
Clearly Labour, the Conservatives, the Liberal Democrats and, in Scotland and Wales the SNP and Plaid Cymru were significant parties, the Greens with 0.9% and 1 seat probably not.
Northern Ireland has a separate party system with two Catholic based and two Protestant based parties.
The number of parties and their relative size. Jean Blondel, the French political scientist, defined party systems around the world on the basis of the number of significant parties. This can, of course, change over time. There may also be a different party system at a sub-state level where a country has regional government.
On this basis a number of countries had a two party system with two large parties having over 80% of the votes and seats in Parliament.
Britain for most of the 19th century was dominated by the Conservative and Liberal parties and, with the decline of the Liberals, a two party system, based on Labour and the Conservatives had developed by 1935.
Other countries, such as Germany, Ireland and Canada had a two and a half party system with a smaller third party providing an alternative to the two main parties.
In the first of the two general elections in 1974 the Liberal Party secured 19% of the vote and 14 seats and Britain could be seen to have moved to a two and a half party system.
The Liberals were strengthened by an electoral pact and then a merger with the Social Democratic Party and have improved further so that by 2005 they had 22% of the vote and 62 seats.
Blondel found that periods where there were three parties of roughly equal size, as in Britain in the 1920s (Labour, Conservative and Liberal) seemed to be unstable and changed to another type.
Many countries, particularly where there was a proportional representation voting system, had multi party systems as in the Netherlands, Finland and Israel. A couple of parties may be larger than the others but here are a number of parties that can get into government in a coalition.
