DFC one more time you show how little you know of the system !
Yes it is quite correct that that all the airlines in the UK do the certification of maintenance via an approval system, that is because they would not issue a type rating for an aircraft under BCAR 8-13.
However it was a requirement to have an engineers licence (without type rating) befor you could go on the approved course to get CRS approval.
To give some sort of idea the course for the Airbus A320 airframe & engine lasted nine weeks. Without this you could not certify a duplicate inspection.
In all the UK airlines that I have worked for (five in all) I have never seen anyone who was not a licenced engineer carry out a duplicate inspection except in componant workshop and that comes under a different approval system.
As to light aircraft I can only think of a few places that non-licenced staff can certify a CRS and they have major overhaul approval for very limmited tasks.
At NO time in this business (30 years) have I seen the CAA "ignore" the requirement for a duplicate inspection on flying controls Etc.