Whoever made that bill up liked 5s I previously worked for a firm where we had to have the estimates we had priced approved by the MD he liked 6s and 9s £3960- £690- £5690 etc. It wasn't a very professional firm to be honest.
...and wire cutters hanging out the back pocket. Finish off the repair by covering the carpet with stripped cable ends
That's our complete roof and re-wire...(done by a cowboy) To solve the problem ,do not go in the loft....
Go up with an extension light or a torch, find that cable and follow it along until you find a junction box. May be a bit black but sounds like a loose connection in there that has touched earth. Worth a try.
I'm no electrician, but I'm struggling to understand why you though that disconnecting the spare room would solve the problem .
If you're getting your Godfather to fix the lights, one day - and that day may never come - he may ask a favour in return...
Ha! Reminds me of a lad I did my sparky City and Guilds with at college - told one of our lecturers that he had installed a twin socket on the side of the bath so he could blow dry his hair whilst sat in the bath..........