OP
WilcoxElec
No, definitely solid yellow - that is what attracted attention, we use loads of different colours for live and returns in France when wires are put in ICA/ICTA tubing in the structure of buildings (the multicoured runs can look quite pretty) , but yellow is not one of them, we can use white so long as we call it Ivoire (Ivory coloured) - and older electriciens like to use lots of that for old times sake... (white and blue is like your red and black to the old hands ).could it by any chance be the 3 core red/blue/white of the 70s which had no cpc(earth),maybe the white has discoloured a bit.clutching at straws but that most definetly had no earth.