Jonathan Lis is deputy director of the pro-European Union think tank British Influence. He writes and commentates on Brexit and politics. The opinions in this article belong to the author.

(CNN) Remember the days when British politics was like its weather and its food? Safely predictable, frequently disappointing, seldom extreme? Those days of moderation are behind us. The fish and chips haven't changed, but everything else has. Stable, dependable Britain has become dangerously unhinged.

And nobody knows why we have to leave on March 29, a date that never once featured in the Brexit referendum. Prime Minister Theresa May declared in 2016 when we would go, and that was that.

Until last week, she was still affirming that she would rather leave with no deal at all than postpone that date, even by a few weeks.

So, what about that no-deal scenario? If, three years ago, you had predicted that the Prime Minister would be threatening an entirely voluntary policy that crashed the economy and necessitated food and medicine shortages, most sensible people would have laughed in your face.

Read More