Not really Brexit related, but the UK does have something to be mostly proud of
https://www.youtube.com/watch?v=139Q61ty4C0
(fair few geeks in here I think that will appreciate this)
Not an electrical geek, but he appears to incorrect about load balancing on a ring mains ('You don't want to have a lot of your power consumed on a portion of the ring. You want to distribute that throughout the ring as much as possible').* So what he claims as a negative is not really the case. The ring potentially allows for twice the current of a radial circuit (for given diameter of cable).
Anyway, certainly not a benefit of Brexit, since these standards existed before, during , and after EU membership. I wonder if we will even find a benefit to Brexit?
But, yeah, I've long admired the British domestic mains plug and socket design. And even more so after I lived in the US.
* Unless there is a highly loaded spur, but he did not mention this. The only other possible issue with balancing is if there is a large load towards one end of the ring (this would disproportionately load the short end of the ring). But even this, in practice, should not be a problem because the mains cable is (or should be) rated significantly higher than the circuit breaker. I expect there are one or more electrical engineers here who will know better than me, so maybe they will comment or correct me.