I really wonder how the last owners lived in this house, we noted the floor boards under the cistern were bowed so found a plumber to fix, plus a few other jobs at the same time, as well as stopping the cistern dropping a floor he also found the shower in the same state below the cistern had to renew beams.
The originally house had a garage below it, but this had been converted into a granny flat, we had been provided with an electrical installation certificate which reading it seemed to cover the whole house, however it seems the granny flat was all it covered, turning off main isolator and main house was still powered, found another fuse box sandwiched between original garage ceiling and new false ceiling.
The central heating got us scratching our head, in the flat there was a wall thermostat, oil boiler, two pumps, and a receiver for a wireless thermostat, in the main house there was a timer, allowing either once or twice DHW or DHW+CH plus all on or all off. However have never found the wireless thermostat, and it did not matter what I did with the time clock the main house heating did not seem to work.
Looking further we found one pump in flat simply plugged into a socket, plugging that in, main house central heating worked, found three core and earth between main house and flat in house red, yellow, blue, in flat brown, black, grey, and one core open circuit.
OK for me easy enough to rewire central heating I installed Nest and so that three core and earth only carries 12 volt at very low current, and now can control heating from the main house, well anywhere where we have phone coverage. We likely the house and location and have been able to correct all faults, but what I wonder is how did the last owners manage when to turn on central heating you had to leave main house walk down steps outside and go into flat and plug in the pump. The central heating used three FCU's and a socket, from two different consumer units. Flat worked OK, but the house was in a right mess. No thermostat.
We think they must have over stretched themselves, as the repairs were not super expensive, but until done not easy to live in the house. We have also found remnants of a garden railway which it seemed at one time when through the house, I thought that was just a 1956's song.