I wonder how much of their valuation the Brexit vote cost them. It might eradicate a good chunk of their customer base. How would one go about modeling this, ho

I wonder how much of their valuation the Brexit vote cost them. It might eradicate a good chunk of their customer base. How would one go about modeling this, how are VCs modeling this? Imagine a company built around some service for expatriates in Britain closed their series A and their series B was happening sometime around/after Brexit. I guess that would be down round territory?