in single phase supplies red will be brown and black will be blue
in 3 phase red will b brown, yellow will be black, blue will be slate and black will be blue. there is a 2 year changeover period startin jan 2004. by jan 2006 all new installations must use the new colouring system
reasons for this is so we use the same colours as the rest of the world, since if u have an electrical qualification in the uk, it is valid thruout the world
as for changes to existing systems, if u do work on a circuit what does not comply with the regulations then that part must be upgraded (even if u change a socket on a circuit, the rest of that circuit must be to the regs) otherwise other circuits can be left (aslong as they are safe)
as for other changes, everything metal in a bathroom must be earthed by a 4mm cable in a ring connected to the earth in a light (not a shower). there were some more stupid changes but i cant remember some f them