Professor Imelda Maher:

Arguably, it will take less time. That is not even in a perfect world. Let us assume there is a Government with which one can negotiate in Westminster. The agreement will take less time because of the point made about familiarity with the structures in the EU and the rules.

In that sense, they have a real advantage over other third countries. One might get away with having a period of five years which would not see too many extensions. The pace of ratification is critical. Even if it is agreed to, they then have to ratify the agreement.