Commentators on the British Constitution sometimes draw a distinction between the Labour Party (which was created outside Parliament and later achieved office) and the Conservative and Liberal parties (which began as parliamentary factions). The term Conservative Party properly refers to the party in parliament, whereas the term Labour Party refers to the entire Labour Party, the parliamentary faction of which is the PLP.
Originally, the Leader of the Labour Party was elected by the PLP. Nowadays, an electoral college is used, consisting of three sections - MPss and MEPs, affiliated organizations (affiliated trade unions and affiliated socialist societies), and Constituency Labour Parties (CLPs). Each section exercises one-third of the vote (meaning that overall, MPs have substantially more say than individual members). Multiple-voting is used, so an MP who belongs to two trade unions, one socialist society, and a CLP receives five votes. The single-transferable vote is used to conduct the election.
Labour MPs retain the power to trigger an extraordinary or "special" Labour Party Conference to choose a new leader if they lose confidence in their existing leader.
Labour MPs also elect two of their number to Labour's National Executive Committee.
The PLP holds regular meetings behind closed doors to question the Leader and to discuss its concerns.
A similiar body for the Conservative Party is the 1922 Committee.