That is simply not good enough. How about if you were working on this same fault and it was coming to you finish time say 17:00. Would you be happy leaving the fault or would you stay and identify and leave power on in a safe manner.
JohnW2 has not suggested isolating all power but to simply isolate the faulty circuit. As a short term solution he stated
provide a temporary supply for anything that can't go without power until the next day
Whats so unreasonable about that?
I know what I would do in my duty of care!
Are you suggesting your duty of care is to restore power to all socket outlets?
Splitting a ring is not difficult and if you are not able to do it in a reasonable time then out of hours call out is not for you, is it?
Maybe so, but it can certainly be time consuming. I would say this could easily require a couple of hours to locate and restore power. Would you agree?
Now imagine carrying out this work early hours of the morning needing in many of the rooms to test when there are people/young children sleeping. What if the rfc feeds both the ground and first floor? Does this seem like a good idea now?