The orange cable is a split concentric cable providing an SNE (TNS) service, the orange outer sheath denotes that it is LSF cable.
The consumers earth should be connected into the earth block provided, not into the service head. I would guess that an installer misunderstood the type of supply and assumed it was TNCS.
As we all know they rather quickly stopped using TNCS for the distribution within a block of flats as it leads to diverted neutral currents flowing through structural steelwork and other services causing all sorts of problems.