Faults central at present !

Been out on a handful of callouts last few days and had some beauties, such as a socket spurred for t.v. and associated sky box, dvd player etc.. spurred from another in a unit which had stopped working and showed up as no neutral ! this was apparently working last week and just stopped working. Took face off socket in cupboard and found all wired from somewhere under floorboards and from 30A 3036 at old board for 1st floor sockets, thing is the cable coming down in wall to the inside the unit socket and spurred to t.v. one is all wired in 1mm twin and earth ! no grommets in metal box etc.. and no N continuity from socket one to board either L & CPC are fine but albeit undersized cable. Left disconnected as need to arrange going back as client wants to check finances first. Also various 3036 shells with 6-7 strands of 5A wire in them to use as a 30A fuse ! I pointed out the fact that the 5A blades / prongs were far smaller area of metal than the 30A ones too ! and also had 5A ones with 15A and 30A fuse wire in them too ! what are people up to ?? Of course it was Mr. Nobody that did it. Also had old black rubber twin and earth which I'm trying to place an age onto and if it's VIR ?? It has something printed on sheath like Henley wiring systems London or similar and inner cores red but dusty looking red and is crumbling like broken biscuits ! so think it could be very old and oils in insulation migrated out or something ?

Trying to work out if worth doing a few tests next visit on I.R. etc.. r1, rn, r2 etc.. and see what's been poked, old and best to replace and or safe enough. Any thoughts, EICR maybe advisable ?
Cheers.