On 12 February 2019, the House of Commons Library published a briefing paper on the mechanics and implications of the UK and EU27 member states unanimously agreeing an extension of the UK's Brexit "exit date" ( currently 29th March 2019 at 11pm UK time) under Article 50 of the Treaty on European Union.
The briefing paper does not come to any particular conclusions but describes clearly some of the factors that the parties need to take into account . These include:-
1. Whether the UK needs parliamentary legislation or approval before requesting an extension of the Article 50 period. Tantalisingly, the paper refers to the possibility ( without, however, endorsing it) that any extension could be requested and agreed to by the UK Government acting under the Royal Prerogative.
2. The circumstances in which an extension might be sought - for example, to enable the UK to continue the Brexit negotiating or clarification process, to pass the necessary Brexit-related legislation, or to hold a general election or referendum.
3. The unique complications caused by the forthcoming European Parliament elections due to be held on 23rd to 26th May 2019 - Would the UK be part of those elections if Brexit were delayed? Would the UK MEPs, if elected, take their seats in the European Parliament , when it sits for the first time on 2nd July 2019? Timing is everything!
The briefing paper runs to 25 pages and will at the very least be mulled over by historians in years to come when the history of the Brexit process comes to be written.