UK Phases used to be coloured as well. The wiring regs changed to make it much less confusing (and cause fewer issues for colourblind people) so that they're now L1, L2, L3.

The GP is also a bit misleading. Most residential properties in the UK are only fed one phase - either the street only has one phase or the grid connects houses up L1, L2, L3 in sequence. Of course I'm speak about detached and semi-detached houses, in larger groups of houses (e.g. blocks of flats) you usually get 3 phases, and one of the jobs of the electrician is phase balancing.