The best known socialist society is the Fabian Society, founded in 1884, some years before the creation of the Labour Party itself (in which the Society participated). The Society's membership is small but, in Labour circles, it exerts significant influence.
Affiliation means that the socialist societies - like a number of British trade unions - pay an affiliation fee to the Labour Party, and the affiliates' members become affiliated members of the Labour Party (a different status from full member), unless they specifically choose not to be. In return the societies receive a formal role in Labour decision-making, and the affiliated members can take part in all-member ballots in certain circumstances: for example, they can participate in the election of Labour Party leaders. The socialist societies also elect a delegate to the Labour National Executive Committee.