I think the point is that there was no compulsion to begin the two-year countdown before any plan was formed or a strategy agreed.

I agree that I don't think another PM would've been obviously more clear thinking. And I also think two years should've been plenty of time, if the government hadn't run the clock down quite so spectacularly. As late as October, EU negotiators were pleading with Britain to figure out what deal it wanted.

But the comparison with Mountbatten isn't invalid: the timing itself is a self-inflicted wound.

I think he is implying that by triggering Article 50 before any preparation has been undertaken you are imposing a 2 year deadline.