Interestingly, the Prime Minister’s belief that she can still persuade Parliament to pass a version of her EU Withdrawal Agreement by 22nd May is reflected at the Hague Conference on Private International Law, regarding the UK’s stance over its accession as an individual state to the Hague Convention on Choice of Court Agreements (2005) and to the Hague Convention on the International Recovery of Child Support and Other Forms of Family Maintenance (2007).
Originally, the UK was supposed to accede to both Conventions as an individual state on 1st April 2019, having already exited the EU on 29th March.
On 28 March 2019, the UK declared for both Conventions that their “accession is suspended until 13 April or 23 May 2019”: a fact that was recorded in notices from the Depository of the 29 March (see here).
The change, of course reflected, the first extension to the Article 50 exit period that was sought and obtained on 22 March 2019 (see here).
Despite the second, subsequent grant of a six- month extension of the UK’s EU Membership until 31 October 2019, there has been no change in the UK’s 28 March declarations. No alternative accession dates have yet been suggested for these Conventions.
Therefore, judging by the Depository Records, as at 17 April 2019 the UK apparently still intends to leave the EU on the 22nd May. The day before the elections to the European Parliament.