In other news.
One private legal challenge has now been launched against Gvt lawyers interpretation that the PM acting alone can implement article 50. The suit contends that that is constitutionally wrong and that only parliament can do this.
It has been anticipated that several other suits will follow.
As discussed a while ago, Mischcon de Reya have a challenge pending on behalf of clients too.
The upshot of all this is that, if pursued to it's final point, this could go to the very top court in the land for a decision.
The only thing that seems sure is that this could drag on for some time yet.