This is NOT the way!
The cables enter through razor sharp holes which should have plastic grommets fitted into them. Here, the metal is free to slice into the cable insulation and cause a fault.
The bare earth wires should be covered with green/yellow sleeving both to identify the wire and prevent the bare wires shorting to either the line or neutral. The installer of these items probably saved 1p by not using the sleeving.
Another similar example, this time a single outlet. No sleeving, no grommets, and the box isn't even recessed into the skirting board properly - not that it should be in the skirting in the first place.
As with the doubles, the wiring is stranded twin & earth with tinned copper conductors. This dates from the 1970s.
This will have the interesting effect of creating eddy currents in the metal box, causing it to heat up.
As with the others, earth sleeving and grommets are not included.