Looking at the first two new photos of the master socket (00076 & 00075), I think I see that the cable entering the dry-liner backing box has a cream (or white) sheath with just four solid colour wires -- the old style blue, brown, green and orange. Blue = B-wire, Orange = A-wire, Green = "bell"-wire. Those two screw-block connectors have been used to connect the newer blue/white and orange/white tails from the B-wire to IDC2 and from the A-wire to IDC5. (Everything is electrically correct but it has not been installed by OR
). The solid green ("bell") wire to IDC3 is unnecessary.
Looking at the first two photos in the bedroom (00079 & 00073), the 700-series connector block (used between 1959 to 1981) is just used to connect two four core cables (blue, brown, green and orange). (It could be where a type 706 or 746 telephone had been connected, prior to BT
's creation and is now used to provide the feed to the bedroom socket.) The third and fourth photos in the bedroom (00084 & 00086) are of an extension socket. The solid green ("bell") wires to IDC3 are unnecessary. Clearly, another extension is "daisy-chained" from the bedroom socket. The fifth photo from the bedroom (00087) is, I assume, the backing box showing two cables with unused brown wires.
The "Bedroom Extension socket (cable coming directly from outside into wall)" (00077) is in another bedroom? and is what we have seen previously (00066 & 00068)?
Extension socket (newest addition):
Blue/w - 2
White / B - 5
Black thick wire has inside:
You have named seven wires in that cable -- which is not correct. It must be eight. No problems, that is obviously an external grade cable.
All in all, still a bit of a mystery. There is some form of star wiring, with modifications made over the years.
100% Linux and, previously, Unix.