if we want to be anal, UK cares a bit because of the GFA, North Ireland peace agreements. An international agreement is a part of those & also it's very importa

if we want to be anal, UK cares a bit because of the GFA, North Ireland peace agreements. An international agreement is a part of those & also it's very important to the UK for various reasons, some even characterize it as de-facto a part of the UK's constitution. And it binds the UK to the ECHR.