An electrician's lot is not a happy one

Armed with a miscellany of test equipment I have been doing a periodic inspection of the wiring in a large house for insurance purposes. There are eight lighting circuits and umpteen power circuits. It is a woeful task removing light fittings consecutively only to find yet-another with no earth, or moving furniture to gain access to socket outlet to perform earth-fault-loop and polarity tests, whilst knowing that there must be many hidden junction boxes that cannot be accessed without taking the house totally apart. At least, although they are fairly old, the cables themselves seem to be in good shape. I can understand the insurance company wanting assurance that the electrics are safe and won't cause a fire, but those inaccessible junction boxes (if they exist at all) are probably the most insidious.