I've no idea how I would've voted in the EU referendum if I'd been a UK resident. However, I have been thinking of late whether large, multi-country agreements (or whatever) are a good idea or not.
NZ has recently signed up to the
TPP, which is a free-trade agreement between 12 Pacific-rim countries. (The signing was in NZ due to it growing out of a trade agreement signed initially between NZ and Singapore. The TPP is yet to be ratified.)
NZ has individual free-trade agreements with countries such as China and Australia. Compared with an agreement with a group of countries, an agreement between two countries is probably easier to achieve and easier to modify if needs be, or exit if that need arises. The downside is you'd end up with many different types of agreements that'd need to be dealt with on a day-to-day basis by businesses and travelers and such.
Those with network-systems expertise can probably say what's the optimum number of countries to have in a free-trade agreement given the number of countries in the world. I've a feeling though that small and nimble is probably better than large and cumbersome, with the repercussions less global when an agreement falls apart.