With less than a week to go until the 31 October Brexit deadline, "no deal" remains the default legal position. The emergency business announcement made during the evening of 24 October by Jacob Rees-Mogg introduced a motion to approve an early general election, to be debated on Monday 28 October. In the same statement, Rees-Mogg confirmed that there are no other changes to the Parliamentary business announced for the remaining few days before 31 October. Further consideration of the Withdrawal Agreement Bill (WAB) remains paused.

In practice, there can be no realistic expectation that the WAB might complete its passage through both Houses of Parliament and receive royal assent before 11.00pm on 31 October. Consequently, there is no realistic prospect of primary legislation to amend or remove the "Brexit Horcrux" provisions added by the European Research Group (ERG) in June 2018 to the EU (Withdrawal) Act and the Taxation (Cross-Border Trade) Act. The WAB passed its second reading debate on 23 October. While that signifies acceptance of the Bill in principle, it does not override existing primary legislation. Similarly, the House of Commons might pass an emergency resolution to avert "no deal", but that would not change the law.

If primary legislation cannot be secured to avert a "no deal" Brexit, then the only remaining method is to agree with the EU an extension to the Article 50 deadline. In March and again in April 2018 the UK government argued that, once agreed, any such extension became effective as a matter of international law. On that argument, the statutory instrument required to amend the definition of "exit day" in EU (Withdrawal) Act 2018, s 20, was merely a matter of tidying up the domestic legal position. Certainly, if the EU were to agree to an extension, the statutory instrument required to amend that definition could be in place before the deadline.

As at 25 October 2019, therefore, the crucial question is whether the EU will either agree to the 31 January 2020 extension requested under the Benn Act, or propose an alternative period. If the EU were to offer a short extension (for example, to 15 November) then that would place the House of Commons under enormous pressure to approve the WAB before agreeing to an early general election.

The government has proposed 12 December as the date for a general election. The timetable dictated by the Fixed Term Parliament Act 2011 means that Parliament would have to be dissolved by 7 November to allow a 12 December election. The WAB would therefore have to receive royal assent by 6 November to ensure that the possibility of a "no deal" Brexit is removed.

From the EU perspective, there must be significant attractions in a short extension. The new EU Commission's term has been delayed to 1 December. Consequently, a November Brexit, with an approved deal, would allow the new Commission to begin substantive negotiations on the future relationship between the EU and UK. From a legacy perspective, the Juncker Commission will also have completed its task of dealing with the first stage of Brexit.

A longer extension might significantly alter political calculations. If the EU were to agree an extension up to 31 January then it would, arguably, be unnecessary to pass the WAB before the outcome of a 12 December general election is known. That election might produce a Conservative government able to claim a clear mandate on Brexit, or conceivably even a Labour government with different objectives. Equally, it might produce an inconclusive result, with exacerbated divisions between England and Scotland, Great Britain and Northern Ireland, and possibly England and Wales. Given that potential outcome, the EU might be inclined to prefer a short extension to maintain pressure in relation to the WAB and (with echoes of 1914) to say that "it will be over by Christmas".