What is a majority and why is it important?

There are 650 seats in the House of Commons. Half of 650 is 325. Therefore, any party that wins more has more than 325 seats in the House of Commons has a majority of the seats. This is then called a majority.

However, the speaker and 3 deputy speakers do not vote. The Northern Irish Sinn Fein party have 7 seats currently but do not sit or vote in the House of Commons. This bring the total number of MPs who can vote down to 639. Therefore, a party needs to win just 320 seats to win a majority.

We calculate the size of the majority but subtracting the number of opposition MPs from the number of government MPs. For example, at the 2019 General Election the Conservatives won 365 seats whilst there were 285 MPs from opposition parties.  365-285=80. The Conservative Party therefore had a majority of 80.

The following graphic comes from the Institute For Government website and demonstrates how the majority is calculated.

Majorities are important because they ensure that the government can pass their legislation through the House of Commons. To win any vote in the Commons, a simple majority is required. Therefore, if the government has a majority of 80, it would require all opposition MPs and 40 of their own MPs to vote against their legislation for it to be defeated. A government with a small majority will find it much more difficult to pass legislation. Between 2017-2019, Prime Minister Theresa May did not have a majority and therefore found it almost impossible to pass the legislation she wished to pass.

A Prime Minister with a large majority can expect to get any piece of legislation they wish passed. Tony Blair won a majority of 179 in 1997 and 176 in 2001. Unsurprisingly, Blair never tasted defeat in the House of Commons until 2005 when his majority had been reduced to 66.

The following graph courtesy of the Institute for Government shows the size of each government majority immediately following each general election: