
On 7 May 2019 the current parliamentary session reached a striking landmark. It became the longest session by sitting days since the English Civil War (1642-51). It was already unusual, having lasted over three different calendar years, beginning on 13 June 2017. As of Friday (10 May 2019) it has run for 298 sitting days, and 2,657 hours and 56 minutes.
This Insight looks at how this Parliament, in particular the House of Commons as the primary chamber, compares to its predecessors. It looks at the number of days and the number of hours Parliament has sat for.
What is a parliamentary session?
A parliamentary session is equivalent to the academic year that you find in a school or a university, or the season for a sport. The session begins when the Queen opens Parliament (the State Opening). It ends with the prorogation, when the Queen’s representatives visit Parliament to announce its end. The next session commences with another state opening. Throughout the twentieth century the general pattern was for sessions to begin and end in October or November. From 2010, with the introduction of the Fixed-Term Parliaments Act, it was decided the new Parliamentary session should begin in May.
However, if a general election has taken place, the sessions tend to run longer than normal. Since 1979 all general elections have taken place between April and June. Before 2010 this meant that those extra months after the election were added on to the normal twelve-month cycle.
How is a parliamentary session measured?
There are two main ways of measuring, and comparing, parliamentary sessions. The first is the number of days that the House of Commons meets (sitting days). The second is the number of hours during which the House of Commons sits (sitting hours).
Sitting days
Since the beginning of the twentieth century the House of Commons has routinely sat for around 150 days a year. The trend has been for the first session, following a general election, to be the longest. Before 2010 the shortest session was consistently that before the general election. This cycle was interrupted by the shifting of the beginning of the parliamentary session to May. The table below shows the number of sitting days in every parliamentary session since 1979-80. Up to and including the 10 May, this current session has run for 298 days.

What makes the 2017-19 session unusual is that it has lasted for more than three years. This has been to permit the passage of Brexit-related legislation. This parliamentary session has now overtaken the 296 sitting days in the 2010-12 session, which was previously the longest since the Civil War. It has therefore also become the longest session since the union of England and Scotland in 1707.
Historically, sessions with a large number of sitting days have witnessed considerable debate on constitutional issues. The single session of the Convention Parliament of 1688-89, which followed the Glorious Revolution in 1688, sat for 250 days. The longest session in the nineteenth century was in 1893-94 (226 sitting days), when Gladstone’s government unsuccessfully tried to enact Home Rule (devolution) for Ireland. In more recent times, the 240-day session of 1992-93 was marked by fierce debates over the Maastricht Treaty that established the European Union. The 1997-98 session, with 241 days, saw the passing of legislation creating devolved institutions in Scotland and Wales.
The Long Parliament
This session is almost certain not to surpass the longest session by days. That was the Long Parliament. It began on the 3 November 1640, and continued, without prorogation, until the 20 April 1653. In total it sat for 3,322 days. Why did that Parliament last so long? Simply put, because it was fighting Charles I in the English Civil War. Subsequently it arranged the trial and execution of the king; and was only ended when Cromwell called in his soldiers to forcibly remove MPs.
Sitting hours
The other way of measuring the length of a parliamentary session is the number of hours sat. Since 2001 the average length of the House of Commons day has fallen. The House has aimed to finish earlier, thereby providing more family-friendly times. But in this session it has been balanced by the longer number of sitting days. The table below shows the total number of hours sat for every parliament since 1979-80. Though the formal figure is yet to be published, the current session – up to the 10 May 2019, is reliably calculated at 2,657 hours and 56 minutes. The final amount will be published after the end of the session.

There are records of the number of sitting hours going back to at least 1831-32. The longest session on record before the current one was that of 1966-67. That session lasted for 2,422 hours and 38 minutes in total. On the 13 March 2019 the current session surpassed that, making this the longest parliamentary session in terms of recorded sitting hours.
A historic parliamentary session
This is an unusually long, and in that respect historic, parliamentary session. Length alone does not guarantee it will be remembered. The 1966-67 session was lengthy, but not filled with drama. Yet it is fitting that a session that has witnessed such dramatic events in Parliament, has also proven the second longest ever.
Further Reading
We would like to acknowledge the help received from the History of Parliament Trust, particularly its director Dr Paul Seaward, with regards to the historical data.
- House of Commons: Hours Sat and Late Sittings, House of Commons Library, 7 July 2015
- House of Commons: Number of Commons sitting days by session since 1945, House of Commons Library, 23 May 2016
- House of Commons: Sitting Hours, House of Commons Library, 5 November 2015
- House of Commons: Sessional Returns, Houses of Parliament website
- Parliamentary Monitor 2018: Time, Institute for Government, 2018
- How long is a Parliament?, History of Parliament blog, 16 April 2019
This post was updated on 25 September 2019 to remove an incorrect reference that stated that between 1987 and 1990 the average parliamentary day was more than 11½ hours. The average length of sitting was only 8½ to 9 hours per day.
About the author: Edward Hicks is a researcher in the House of Commons Library, specialising in local government.