The next largest party becomes the Official Opposition. The other non-government parties are also called opposition parties. If an MP does not have a political party, they are known as an 'Independent'.
Members of the House of Lords are organised on a party basis in much the same way as the House of Commons but with important differences: Members of the Lords do not represent constituencies and many are not members of a political party.
Lords who do not support one of the three main parties are known as Crossbenchers or Independent Peers. There is also a small number who are not affiliated to any of the main groups.
History of the party system
The system of political parties, which has existed in one form or another since at least the 18th century, has been a central element in the working of the constitution. Since the Second World War, all the Governments in the UK have been formed - or led - by either the Labour Party or the Conservative Party.
The day to day work of the Commons often depends on a working relationship between the Government and the Opposition - sometimes referred to as 'the usual channels'. However, the role of the Official Opposition is to challenge the Government, to make sure an alternative viewpoint is expressed and to act as a 'government-in-waiting', ready to take over, should the Government lose the confidence of the House.
While in opposition, parties in both Houses generally aim to:
contribute to the creation of policy and legislation through constructive criticism
work together, where possible, to oppose government proposals they disagree with
put forward their own policies and try to win concessions from the government
Where do MPs sit in the Commons?
MPs from the same party tend to sit together in the House of Commons Chamber. The Chamber is a rectangular shape so the Government and the Opposition can face each other. The Government sits on the benches to the right of the Speaker. The official Opposition and MPs from other parties sit on the benches to the left of the Speaker.
Where do Members of the Lords sit in the Lords?
As in the Commons, the Government and the Opposition face each other. The Government and the Bishops sit on the right of the Lord Speaker. The Opposition parties sit on the benches to the left of the Lord Speaker while the Crossbench Peers sit mostly on benches that cross the Chamber of the House of Lords behind the clerks' table.
Frontbenchers and backbenchers
In both the Commons and the Lords, Government ministers and Opposition shadow ministers sit on the front benches and are known as 'frontbenchers'.
MPs and Members of the Lords who do not hold ministerial positions sit towards the back of the Chamber and are known as 'backbenchers'.
Independent MPs and Crossbench and Independent Lords
MPs and Members of the Lords do not have to belong to a political party. Instead, MPs can sit as Independents and Lords can sit as Crossbenchers or Independents.
Bishops in the Lords
The Anglican Archbishops of Canterbury and York, the Bishops of Durham, London and Winchester and the 21 other senior diocesan bishops of the Church of England have seats in the Lords. This is for historical reasons. When they retire as bishops their membership of the House ends.
Crossing the floor
Members of either the House of Commons or House of Lords can change political party at any time - known as 'crossing the floor'. The term comes from the fact that, traditionally, Members of Parliament from opposing parties sit on opposite sides of the Chamber.
Therefore, a Member who changes party usually has to cross the floor of the House to sit on the other side of the Chamber. The term is used to signify the changing of allegiance.