But the planned date for the start of the Commons’ summer recess remains unannounced. During questions on his first Business Statement on 6 June, the new Leader of the House, Mel Stride MP, followed his predecessor in declining to name a date.

Recent timings of the Leader’s announcement of planned summer recess dates have ranged from February or March – in 2018 and 2016, respectively – to 28 May in 2015, and 20 June after the general election in 2017.

The government’s proposed recess dates must be approved by the House, on a motion for a periodic adjournment, moved by a minister (Standing Order No. 25). The planned dates can change until the government tables its motion, which it must do only by the rise of the House on the day before the day on which it wants the motion approved (this is to meet the deadline for getting an item of business onto the Order Paper). The day on which the government asks the House to approve the motion can be the day of the planned adjournment itself.

The House cannot amend an adjournment motion moved by a minister, but it could force a division and vote the government’s motion down.

While the start date for the summer recess remains unknown, a focus of questioning during 6 June Business Questions was whether this would at least come only after the new Prime Minister is in place.

Mr Stride twice declined to give a commitment to this effect. However, after Mr Stride’s statement, No.10 reportedly told journalists that the House is still expected to be sitting when the new Prime Minister takes over.

This sequencing still does not make the timing of the summer recess certain.

For one thing, there has been speculation that the Conservative leadership contest might not run all the way to the week of 22 July.

More importantly, there is the question of what, if anything, the new Prime Minister may wish to do in the House before the summer break. This could have implications for the timing of the recess.

During 6 June Business Questions, much of the interest in whether the House will still be sitting when the new Prime Minister takes office came from opposition MPs.

As long as the House is still sitting, the Official Opposition can table a motion of no-confidence in the government and, by well-established convention, see the government quickly provide time on the floor of the House for it to be considered.

If the House is still sitting, and if the new Prime Minister were appearing reluctant to appear before it, MPs could also seek an emergency debate (under Standing Order No. 24) or an Urgent Question (under Standing Order No. 21(2)) to exert pressure on the new Prime Minister to do so.

However, outside specified types of business such as these, or certain special circumstances, the government determines the business that the House considers, and when. As Mr Stride appeared to suggest on 6 June, the new Prime Minister’s wishes in this respect could therefore affect the timing of the summer recess.

On the one hand, the new Prime Minister might welcome the opportunity offered by the summer break simply to get his or her feet under the table before testing the mood, or certainly the opinion, of the House. If the Official Opposition had not tabled a no-confidence motion, and the House approved the motion for the periodic adjournment, the government could adjourn the House pretty much immediately after the new Prime Minister is appointed, with no particular proceedings arising from the change of administration.

However, if the new Prime Minister were to seem reluctant to appear before the House, or perhaps test its views, he or she would run the risk of being seen to be, in Mrs Thatcher’s terms, "frit". This would not be an auspicious start to a premiership, and could set the tone for a relationship with the elected House that will be critical to its prospects of success.

Moreover, given the circumstances in which the new Prime Minister will attain office, he or she might well want quickly to demonstrate that he or she has the confidence of the House.

The most straightforward way for the new Prime Minister to do this would be to move a motion of confidence in his or her own government.

Might there even be a possibility of a quick Prorogation and Queen’s Speech? With five days normally given over to the Commons’ debate on the Address in response to the Speech (which requires approval, and is amendable), this would have greater implications for the parliamentary timetable.

As regards Brexit, it is hard to see even a 'pro-deal' Prime Minister introducing the Withdrawal Agreement Bill, or taking another run at a Withdrawal Agreement approval vote, without having held discussions with the EU. (Assuming that there had been no Prorogation, the second of these would in any case risk running into the 'no-repeat-decision-in-the-same-session' rule.)

But there would be nothing to stop the new Prime Minister from moving a motion seeking the House’s approval for his or her proposed Brexit approach. Indeed, from an international negotiating perspective, there would be much to recommend demonstrating to the EU that the new Prime Minister can command the House, and has a degree of consensus behind his or her policy. But this would depend on the motion passing, and the policy being one capable of negotiation.

Under the circumstances, any of these possible routes by which the new Prime Minister might win the support of the House on a substantive motion could, for him or her, be fraught with risk.

This collection of factors means that the House of Commons might see some significant business once the new Prime Minister is in place but still this side of the summer break. This in turn might see the start of the recess delayed beyond the accustomed time.

Before the new Prime Minister is in place, the immediate question is how to fill (probably) six weeks of time on the floor of the House of Commons until the week of 22 July.

There will, of course, be the normal question times and government statements, including the Prime Minister’s after the 20-21 June European Council.

Select committees will remain busy, with the election of a new chair for the Northern Ireland Affairs Committee on 12 June a particular point of interest, as well as the usual rush to publish reports before the summer.

But the 6 June Business Statement confirmed that, as regards the thinness of the government’s legislative business, nothing has changed with the change of House of Commons Leader.

The absence of the Withdrawal Agreement Bill that finally caused Theresa May’s downfall is the immediate source of the problem. The Bill was due to have had its second reading in the week of 3 June, until Mrs May decided she was unable to introduce it.

But two older factors lie behind the government’s lack of legislative business, namely: the length of the current parliamentary session, and the government’s inability to move further stages of various Brexit-related bills.

These two factors are combining to produce government primary legislative business in the Commons that is mostly either finished or stuck:

13 June marks two years since the start of the 2017-19 parliamentary session. The legislative agenda announced in that's year's Queen's Speech is virtually exhausted. Of the 24 bills in the 2017 Queen’s Speech, all but seven have achieved Royal Assent. Of those seven, four are Brexit-related; and of the remaining three, one has been abandoned, and one completed its Commons stages on 10 June and will go to the Lords, leaving only the High Speed Rail (West Midlands – Crewe) Bill still in the elected House.

Other bills, not outlined in the Queen’s Speech, have also achieved Royal Assent or have completed their Commons stages or are close to doing so. And few new bills are being introduced to replace them.

Moreover, such bills as are going through the Commons mostly address important but relatively narrow issues, and are not flagship pieces of legislation; the Parliamentary Buildings (Restoration and Renewal) Bill is the only major piece of government primary legislation recently introduced.

Overall, there are 15 government bills with unfinished parliamentary proceedings. Of these, five are stuck Brexit bills. Of the ten non-Brexit-related bills, three have now completed their Commons stages and are in the Lords; only two are in the Commons with the Lords still to come; and five started in the Lords and are yet to come to the Commons. This last process should at least generate some primary legislation for the Commons to consider if the parliamentary session does not end soon, although, again, none of the five is a major piece of legislation.

Of the five Brexit bills that have been introduced but not yet achieved Royal Assent, the Trade Bill has been awaiting Commons consideration of Lords amendments since March; the Financial Services (Implementation of Legislation) Bill has completed its Lords stages but had its Commons report stage pulled, also in March; and the Agriculture, Fisheries and Immigration Bills have been awaiting their Commons report stages since November, December and March respectively, and are yet to go to the Lords.

A critical difference to the parliamentary workload, as well as the Brexit process, could be made by whether the new Prime Minister seeks to pass any of the stuck Brexit bills before 31 October. These bills were introduced as major elements in the UK’s Brexit process, but on 10-11 April the country was within 48 hours of leaving the EU without any of them having been passed.

Before the summer, is there any non-Brexit business that must be taken on the floor of the Commons, to help fill the legislative gap?

The only item we can think of so far is the approval of remaining estimates (of government spending).

To be approved under the procedures normally used for estimates, all the year’s remaining estimates must be approved by 5 August.

The process comprises debates and votes on selected estimates on 'estimates days', on motions that may be amended only to reduce the amount of spending authorised; a vote on an unamendable 'roll-up' motion for all remaining estimates; and passage of the Supply and Appropriation (Main Estimates) Bill, which may not be amended and thus has no committee stage.

The number of 'estimates days' this session has already been raised from the normal three to five, to accommodate the session's two-year length. All five days have already taken place. A further two days are now expected to be added, to allow this session’s third set of summer estimates proceedings to take place according to normal practice in early July (i.e. before the new Prime Minister is expected to be in place). The deadline is 14 June for MPs to nominate, through the Backbench Business Committee, the estimates on which the two new days of debate should be held. However, the pre-summer estimates process will still only make up a total of three days of business, since – after the two estimates days – the second and third reading of the Supply and Appropriation (Main Estimates) Bill are taken without debate on a single day.

Reflecting the lack of government primary legislative business, the Commons is sitting for less time than normal (although this is admittedly a crude measure of activity): the House’s average daily sitting time was 7 hours 41 minutes during the 2015-16 session and 7 hours 32 minutes in 2016-17, but 7 hours 39 minutes in April 2019 (7 hours 20 minutes if the 11-hour day of the Cooper Bill is excluded) and 6 hours 42 minutes in May.

However, the government appears to be trying to keep time filled by allowing more non-government business. During the last Business Questions before the Whitsun break, the Chair of the Backbench Business Committee, Ian Mearns MP, called the parliamentary week of 4 June "the very first backbench business week in this place". He confirmed that his committee had had “at very short notice to pull together business [from the backlog of requested backbench debates] to fill the void” left by the non-appearance of the Withdrawal Agreement Bill.

The chart below shows, for example, that the week of 10 June is the fifth in succession in which there have been at least two backbench debates. Most notably, since late April, opposition days have reappeared, after a five-month hiatus. (The chart only displays whether there were any post-first-reading proceedings on government bills on the floor of the Commons, so it does not show the lack of new or major primary legislation specifically.)

Sources: House of Commons Votes and Proceedings; Order Paper and Future Business, 7 June 2019

Under Standing Orders, the number of both backbench business days and opposition days are subject to minimum quotas per session, rather than maximum limits.

Of the 20 opposition days due under Standing Order No. 14(2), the Official Opposition has already had its share (17), and there are only one-and-a-half still to be held of the three days that go to the smaller opposition parties.

However, as a result of running a two-year session, the government has been granting ‘unallotted’ (i.e. non-quota) opposition days and half-days since January 2018.

The time on the floor of the House that the government is granting to the Backbench Business Committee is also already over-quota for this session – but the Committee normally appears more than able to fill the time made available to it.

In the context of the current Brexit debate, both backbench and opposition days could present opportunities to those MPs wanting the House of Commons again to express its opposition to a ‘no-deal’ Brexit, or perhaps take procedural steps to make one less likely.

Both backbench and opposition day debates on the floor of the House can be held on substantive motions (and, in the case of opposition day debates, usually are).

There is no specific requirement that House of Commons business motions must be moved by the government, and no specific prohibition on moving business motions on opposition days (although this has not been done). Motions taken under backbench business may not amend Standing Order No. 14, which governs the arrangement of business in the House, or Standing Order No. 152J on the Backbench Business Committee itself, but there is no specific restriction on these motions seeking to amend or set aside other Standing Orders.

A further opportunity, this time for the Liaison Committee, could arise under a current pilot arrangement. With the agreement of the Backbench Business Committee, the Liaison Committee is due to nominate the backbench business to be taken on the floor of the House on a number of days equivalent to the number of estimates days. (This is a 'swap' in return for the Backbench Business Committee gaining the right to nominate business on estimates days, which previously fell under the Liaison Committee’s remit.) So far, under the pilot (which the Procedure Committee is currently evaluating), three days’ worth of backbench business nominated by the Liaison Committee have taken place. A further day could well be allocated before the summer break. (The days so far with business nominated by the Liaison Committee were 26 April, 17 May, 28 June and 6 September 2018. For the purposes of the chart above, the last of these was counted among the backbench business days.)

Liaison Committee access to backbench business days was envisaged as allowing debates on the floor of the House on substantive motions relating to select committee reports – a significant innovation in itself. But, again, there appears to be no procedural obstacle to these debates taking place on a substantive motion on a policy or procedural matter, to which a select committee report or reports could be tagged. The April 2018 debate was held on a motion, moved by Home Affairs Committee Chair Yvette Cooper MP, which called on the government to make a UK-EU customs union a negotiating objective.

An important constraint on the use of backbench business days for 'no-deal' Brexit-related business could be the appetite of the Backbench Business Committee, or the Liaison Committee for a further time, to make their access to the Commons Chamber available for a substantive debate on an issue which is so contentious within the House.

For all the opportunities that backbench business or opposition day debates might afford, they also highlight the limitations on non-government business on the floor of the House of Commons.

For one thing, only some House of Commons bodies can claim time in the Chamber. The Petitions Committee can refer an e-petition for debate only in Westminster Hall, for example. No departmental select committee has direct access to time on the floor of the House but must proceed via the Liaison Committee or Backbench Business Committee. (This contrasts with the access of Lords select committees to time on the floor of the Upper House.)

Select committee business on the floor is also limited by deadline constraints. Under Standing Order No. 22D, a committee chair can make a statement in the Chamber and take questions on a new report or inquiry, but usually only for around 15 minutes, and only on full backbench business days and only within five sitting days of the report or inquiry being launched. This is especially problematic for reports published just before recesses, for example.

Most importantly, the vast majority of time on the floor of the Commons remains under government control, and the timing of such non-government business as is possible remains at the government’s discretion.

As has been pointed out in the current ‘no-deal’ Brexit debate, the easiest way for the government to avoid any risks arising from opposition days or backbench business is simply not to grant them.

But this does not address the question of how the government is going to fill time in the Commons Chamber, given the state of its legislative programme.

The dearth of government primary legislative business could present an unusual opportunity for some further procedural experimentation to allow more non-government business in the Chamber, although, obviously, the government's fragile political position could weigh against this.

Most straightforwardly, the government could simply allow more opposition and backbench business days. In theory, the government could move a motion to amend Standing Orders to provide for a new minimum number of opposition and/or backbench business days for the rest of the session, or it could at least make an announcement to this effect, although the change would demand a degree of certainty and tolerance for risk that is probably unavailable.

But the restrictions could be relaxed on a trial basis on select committee statements on the floor of the House, for example. Or a trial introduced of some dedicated select committee time, not confined to existing backbench business procedures.

On any matter, there is nothing to stop the government from moving a motion temporarily to amend or set aside relevant Standing Orders.

Opposition and backbench business days could thus present opportunities to MPs opposed to a ‘no-deal’ Brexit on 31 October. The lack of government legislative business, as well as the Brexit timetable, suggests that MPs would do well to take such opportunities before the summer.

But the thinness of the government’s legislative programme means that the period between now and the recess also presents an opportunity for some trial procedural innovation in the Commons Chamber that could be valuable whatever happens with Brexit.

The focus on the end of the pre-summer parliamentary period is understandable, but the six weeks before then could represent an opportunity that it would be a shame to waste. Just because Brexit policy and much other government business is in abeyance pending the arrival of the new Prime Minister, there is no reason for MPs not to try to use the parliamentary period before then to put down policy and procedural markers that could come into play when the new Prime Minister comes to office and beyond.

Fowler, B. (2019) Waiting for who? House of Commons business before the summer recess (Hansard Society: London)