No problems what so ever, as DD these were council houses we were an approved company with the nic no DI back then.
I was an apprentice so dont know the full details, but the council must of inspected the work and it may have even been in the spec (who knows).
As mentioned previously it was much quicker and no real disruption or mess, just to add the old rubber cables we provided in the cavity from build it was like for like replacement.
I am not going to go into the rights or wrongs into this practice. As explained the council tenants were more than happy as the houses was not ripped apart no redecoration etc.
So I would expect the council inspectors were satisfied to.