There should be clarity on these changes of colours to make all aware of what goes where
I posted this a few years ago
In older times,the 3 live conductors were coloured Red ,White, Blue, the Black was neutral and a bare earth
These then changed to Red Yellow Blue,it was much the same but the White had been replaced by Yellow with the Black hanging on to its neutral tag
As we are aware,yet another change means at present, a live may now be Brown, Black or Grey and the Blue neutral (or the neutral could even be a Grey that is over sleeved as Blue)
This Blue has replaced the Black in older systems for single phase, however, it remains as a live for 3 phase with those older systems, not forgetting the Green/Yellow which as superseded the Green
In order not to complicate the matter. but for reference, the bare earth that was Green and is now Green/Yellow, may in fact be Cream if you use a lot of IT eqipment
Other colours are not precluded, as long as coloured identification is used unless its single core which must be green/yellow
So put concisely
The live may be Brown, Red, White, Black, Grey, Yellow or Blue
The neutral may be Black,Blue or even Grey
However, colours for central heating control systems may be unfamiliar to some
Be familiar with this information before attempting electrical work