When Brexit talks resume in Brussels in mid-August, British and European officials will have just 10 weeks to finalize the complex set of international negotiations before their October deadline. That’s because they need to leave time to ratify whatever agreement emerges in both the U.K. and European Parliaments before Britain exits the bloc on March 29 next year.

It’s a tough ask and in private, ministers and senior officials in May’s team are terrified that the negotiations will fail…

“I have near zero optimism because I think it is going to be very messy,” said one senior minister, speaking on condition of anonymity because the matter is so sensitive. The prospects of getting an agreement are slim, the minister said. “If we crash out without a deal, it’s going to be a historic catastrophe.”