'Twas brillig, and the slithy toves did gyre and gimble in the wabe

It *partially* makes sense. The rest of europe picked brown-blue, when we picked red-black. When we went 3-phase we decided on yellow on blue for the other phases. Which apparently is not good for those who are colourblind (and probably should then be in another profession, but this was before the days of political correctness).

Europe became the EU, and then decided to harmonise colours for 3-phase kit. Now, since this is the age of political correctness, they decided to go for colours which colourblind people can tell apart. Which is why they added black to the phases, and then grey. And of course since .uk is part of the EU, we should adopt their colours.

The whole thing only falls apart when you consider the UK, and the fact that we've had blue and black the other way round for decades.