Will there be any positive consequences that are expected from Brexit or is it mainly expected to be bad for the British trade?
If the question is "... has affected ..." and not "... will affect ..." you will have to look into the effects of uncertainty.
- Google about companies in a just-in-time transport loop which are stockpiling more supplies, if they can.
- Google about decisions being postponed.
- Google about companies (banks, airlines) opening EU-based headquarters in addition to their UK-based offices.