So i did the consumer unit swap today and as usual start with testing the circuits one by one and after last one i realized that i forgot about one socket on the hallway. At that time all cables where out of consumer unit. So i cross connect L-E and went to do R1+R2 just to find out that socket is live. It is maisonette and seems like when they convert it they forget to remove one socket. I could not get in to the other flat so left it for now. Customer is aware and i told her not to use it. I am planing to come back and blank it for now and put note on it. Am i right thinking it will be other resident responsibility to get that disconnected from her side at her own cost? Anybody come across that in the past?