The fuse carrier appears to be one of the later plastic types which has been substituted for the ceramic one which would have been in this MEM unit originally (matching the rest of the "innards" in color).
I don't think those later carriers will actually seat properly in the older units, will they? That could account for a lot.
the extra Phase and Neutral conductors fitted tot he incoming side (bottom) were feeding another disco that then went on to feed an AIR CON unit,
What's the betting that those were just cut live when the air-con feed was no longer needed? Looks like somebody left the on/off tag from the other switchfuse in the bottom of this box too!
