Hello Lawence,
If there is an electrical fire there was something else unsafe with the domestic wiring,(Earth Bonding?) or an Applience fault which did not activate either the RCD or related MCB. This is where a 10year Periodic Check Inspection is worthwhile. Every EVEN year, 2024 - 2026, at Christmas I go around all my sockets and lighting switches and check tightness of terminations. I also have the test equipment to verify RCD function and check the earth loop impedence is within spec.

The addition of the pure silver Buss Bar to the existing Live copper Buss Bar raises the total current rating from 100A to 200A, it is more robust.
Likewise a 1.5mm pure silver wire strand will easily carry 30A per strand, and with 3 or 4 bunched together, combined with the existing Neutral wire link from the ON /Off Switch makes this connection more robust, again about 200A.
If you have doubts get a Qualified Electrician, not a Sparky, to inspect this. If they do not know the answer to this question they are a Sparky. Why is the Earth wire in T&E cable located in the middle and not on the outside?
I will not be posting the answer!

Regards
Roy