disabling a socket

Asked electrician to remove a socket from the kitchen wall, so we can tile over it. On completion of the job I asked if it was now safe to tile over. He said it was, \\\'everything is insulated\\\'. I asked if that meant the actual wires were still live to which he replied that they are as it\\\'s all \\\'on a ring\\\' and they can\\\'t be cut off completely. Is this right??? It occurs to me that if at some time in the future someone decided to drill there (for whatever reason) they could come to grief.

No, its not good.
If for some reason cables cant be removed from ring the very least you have to do is put a blanking plate on existing box.

Is the join in an allowed area? This is vertically or horizontally in line with another accessory switch/socket/fused spur or 150mm from the ceiling or corner of the room?
If it is then it could be Ok assuming it is well insulated ie. with heatshrink/self-amalgamating tape.