DaisyAnne
The negotiators are not generally politicians, are they WWM although they may have one with them.
I have no idea how the politcal tectonic plates may have changed re Iran/Russia/UK . On the principle of "my enemies enemy is my friend" perhaps things have moved just enough to make this possible.
No they are usually civil servants. My concern is (although I guess this is a different department) that many of those skills were lost when we were members of the EU. All the professionalism resided in Brussels for all members to call on when necessary.