EFLImpudence has nothing to add to this thread, except noise. I fear he doesn't know. Maybe he thinks he is the Part P Police. I would advise most people to do homework first as if you get three electricians in, you will get three different solutions and different interpretations of the regs. Most electricians did not know earth bonding before the 17th regs. I knew one who insisted that the bathroom bonding HAD to go back to the meter. Even I knew it did not and that the appliance in the bathroom just needed to be linked to each other. Another who would run cables over kitchen worktops behind the tiles horizontally. Read the threads on here and see the different interpretations. Electricians generally are a poor trade craft-wise, just look at the appalling state of the wiring around most meters that are slapped all over with no idea of neatness and not even clipped. 25mm cables loose so kids can pull them off.