Thank you for all the replies, I will indeed keep to just the one thread, at first I thought they were separate issues but I have come to realise they are all aspects of the same horrid mess!!
The first job I did today was to separate the two 7/029 VIR's at the CU & test for ring completeness with nothing whatever connected to any outlet and they did form a ring so thank god not radials. I also tested the insulation at the low DVM voltage and got infinity on both L-N & L-E, so far so good. The trouble started when I decided to separate the two lighting lives for an insulation test and lo some of the insulation fell off thus confirming it is indeed in a parlous state.
This convinced me a rewire was imminent so I set about the laminate flooring in the bedroom above the CU, when some boards were lifted there were some unpleasant surprises given both the sockets in this room had previously been checked and found to be wired in pvc and hence put on the good list, well the pvc lasts for about a foot, just enough to get under the boards where it joins onto the rubber with JB's, I have never seen the like, this is either a fraudulent re-wire or the previous owner having a joke!!
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There was just one bit of good news and that was the cabling up from the CU is in trunking so it should be possible to pull in new without having to chase the wall, I just hope this is also true for downstairs sockets, light switches etc
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I will get a full re-wire underway as soon as I can find a qualified professional to do the job.
P.S. it's plasterboard not lathe & plaster as I thought it might be, I remember an earlier post about that.
EDIT
And are they mouse droppings or bits of crumbling insulation from this bend
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