There are two ways that a parliamentary session can be brought to an end—dissolution followed by a General Election or prorogation by the Crown. (“Just as Parliament can commence its deliberations only at the time appointed by the Queen, so it cannot continue them any longer than she pleases.” (Erskine May, 2019, p165))
Dissolution is controlled by the provisions of the Fixed-term Parliaments Act 2011 which provides that the period of a Parliament between general elections is five years unless at least two-thirds of MPs vote for an earlier dissolution or the government loses a vote of confidence.
Erskine May defines a session as “the period of time between the meeting of a Parliament, whether after a prorogation or dissolution, and its prorogation” (2019, p164). The 2011 Act says nothing about the length of sessions.
Sessions are of an indeterminate length. Prior to the 2011 Act, sessions generally ran from October or November of one year to October or November
