The GPA members and the UK have reached an agreement allowing for the country to acceed to the Agreement if and when it leaves the European Union. This agreement ensures a continuity of the international procurement legal regime for UK-based undertakings and those based on the GPA members.
Back in 2017 myself and Albert Sanchez-Graells concluded that the UK was not a party to the current GPA in its own right and would have instead to apply for accession. Our colleague Ping Wang from Nottingham reached a similar conclusion.
In the paper we posited that the accession could follow a streamlined process but we assumed that even then it would take a significant amount of time. In this instance we were proved wrong, with the accession ocurring quicker than we anticipated.
Regarding possible change to the UK's legal regime(s) post-Brexit, we remain convinced that the accession to the GPA limits the scope of the changes that can be introduced.