My take on this is that any paid work being done, no matter the location, comes under HASAWA and EAWR, this includes domestic properties.
Because the requirements are to maintain safety, this must be done during the works and can be achieved, electrically, by following BS7671.
Therefore, only if there are no changes, after the work has finished it must not present a danger; if it does present a danger then the work that was being done was not, at that time, in accordance with the law.
In that respect the HASAWA and EAWR do apply to the work once it is completed (but most defences would claim later changes had been made!). However when no one is actually working in a domestic property the HASAWA and EAWR do not apply to what is happening in the present, only to the effects that had happened in the past.
Regarding SWA I do not believe it is required to earth the armour, that is not being used as a cpc, at the supply end; it is just best practice. The shorter fault path leads to better compliance with the minimum standards of BS7671 by reducing the impedance of the fault path.
Earthing the armour at both ends, when it is not a cpc, may lead to circulating currents through the armour, but the level of disadvantage must be weighed up against the advantages of having two earthed points on an exposed conductive part.
However where the two ends are in installations with different earthing arrangements then 542.1.3 applies and the supply end only must be earthed.
The default case of the armour as a cpc clearly requires continuity and therefore earthing at both ends.
