The AC hum of 50 Hz in Europe is close to
the pitch of G1 = 48.99 Hz (49 Hz). The AC hum of 60 Hz in the U.S. is a minor third higher
close to the pitch of A1/B1 = 58.27 Hz (58 Hz).
So you can find out logically, whether a sound recording was made in Europe or in the U.S amongst others if you are really interested.

I doesn't depend in the least on Brexit, thank goodness, Deo Grati
However I wonder if the Trump administration will include a mandatory change in the next trade deal?
Just a thought .