The length of a session

This paragraph (or sub-paragraphs) have been updated, added or deleted since publication of the 2019 edition. Any sub-paragraphs updated since the 2019 edition can be highlighted by clicking ‘Highlight updates’ below. The most recent updates to this publication were made on August 2021. See the summaries and schedules for each successive update from the Home page.

18.2Chapter 8 has described how the period of a Parliament, between two General Elections, whether lasting the maximum five years or brought to an end earlier, is divided into sessions. The ends of sessions are marked either by dissolution or prorogation. Dissolution of Parliament is brought about by Royal proclamation under the prerogative or at the beginning of the day that is the fifth anniversary of the day it first met.A1

Prorogation is a prerogative act. In other words, unless it is brought to a conclusion by a dissolution and General Election, the duration of a session is determined by the Government. The Government's freedom of choice in this matter is, however, circumscribed both by convention and by the necessity of passing certain items of business in accordance with the procedures set out in standing orders and elsewhere.

Following the passage of the Fixed-term Parliaments Act 2011, sessions have tended to end in late April or early May and begin in mid to late May. Previously, they had mostly begun and ended in October or November, except where there had been a dissolution.1 The session in which the Act was passed lasted for two calendar years – from May 2010 to April 2012. The sessions which began in June 2017 and in December 2019 also lasted for well over a calendar year.

The House has generally adjourned for a week around the date of the Spring Bank Holiday or later that month; then again from late July until early to September when the House has returned for two weeks, then adjourned once more while the annual conferences of the major political parties are in progress.2 The House has resumed sitting in early October until the week before Christmas, with an adjournment of a few days in the first half of November. The House typically resumes sitting in January following an adjournment of about two weeks. There are normally then further adjournments of a week around the February school half-term and for about two weeks around Easter. Parliament then prorogues in late April or early May, with the new session opening a few days later.3

Since the reduction in the number of sitting Fridays (by change to Standing Order No 12 in 1995), the number of days on which the House has sat in a normal session (ie sessions lasting approximately a year) has varied between 133 and 182. The shortest session since 1945 was 1948 (ten days) and the longest that of 2010–12 (295 days).4


  1. 1. From the summons of 15 June 1945 to the dissolution of May 2017 there were 19 Parliaments totalling 72 sessions. For discussion of earlier patterns, see Erskine May (14th edn, 1946), pp 294–96. Until the middle of the twentieth century it was not uncommon for new sessions to begin after Christmas.
  2. 2. The House did not sit in September in the years 2004 to 2009 but resumed in 2010 following a recommendation of the House of Commons Reform Committee, First Report, HC 1117 (2008–09) para 101; CJ (2009–10) 241.
  3. 3. Where, as is generally the case, provisional recess dates have been announced significantly in advance, then the expected dates are published on the Parliament website (and a printed calendar indicating expected future sitting days over the coming months or year may be issued).
  4. 4. The numbers of sitting days in each ‘normal’ session since then have been as follows: 1995–96, 146; 1998–99, 149; 1999–2000, 170; 2002–03, 162; 2003–04, 157; 2006–07, 146; 2007–08, 165; 2008–09, 136; 2012–13, 145; 2013–14, 162; 2014–15, 133; 2015–16, 158; 2016–17, 142.
  5. A1. Dissolution and Calling of Parliament Act 2022, ss 2 and 4.