Consumer unit/ cable identification /gap fill

[Schmoogle]

Anyone tell me what the black cable is? I need to fill the hole below (mice ingress); there is a cable in the hole. I’d like to identify it (and insulate appropriately) before I fill gap with mortar.
Any help appreciated!

 

[gman76]

I would say that is an earth bond that goes to a water or gas main, which is interteresting as the supply looks like it has been updated from TNS to TNCS. What the implications (if any) of this are - I'm not sure.

The wire looks to be green which has darkened with age.

Hopefully someone who knows more than I will come along now that I have bumped the thread.......

 

[Taylortwocities]

Its an earth cable, possibly a bonding conductor. Impossible to say if it is still required from a photo.
Needs inspection of the connections inside the (newish?) consumer unit and also trace where the mystery cable goes to.
Wherever it ends up, it's too small for its purpose, if indeed it is still in use.